Case Head Exits Rifle

You guys did should a good job on my last poblem, I thought I might share an experience that I still don't understand.:sos: My first "big bore" rifle was a 7mm Rem Rolling Block. I didn't like it and I sold it. A few years ago I bought two 7mm RRB's to play with. I made one into a hunter ala de Haas.:thup: I fit the barrel to the receiver with essentially zero clearance between case head and block.:super: No headspace problem at all (finish reamed it myself). I buy two boxes of 7mm commercial ammo. No problems, good accuracy. ;) When I reloaded these cases, I noticed a lot of case stretch.:confused: Had to full length resize and trim more than normal for a single firing. Out come the GO/NO_GO's. No headspace problem with very minimal headspace. Trimmed the once fired cases and loaded them up.:beerchug:

Ist handload, which was relatively mild, the case head blows off and hits me in the forehead right above my left eye so hard I was stunned - cut to the skull, blood everywhere - wife freaking out.:bow: I thought the RRB had blown up. Nope. It was in fine shape with minimal headspace. I put the rifle in the safe and left it for a year.:surrender: Recently I pulled it out, and tried handloads again. Every reloaded case parts or begins to part, but none have exited the rifle has did the first one. I can only use new brass in this rifle.:crying:

The loads are 3 grs from published max, so pressure is not the problem. My question is: How did that case head come out of the block? A 0.001" feeler gauge won't slide between the case head and the block and there are no signs of excessive pressure whatsoever.:ugh:

My question for those familiar with RRB is how did that case head exit that receiver block without damaging the receiver? I thought the RRB's were case hardened. A RRB locks up tight as a drum.:D

My take is that only new brass can be used once, as the case stretches so much that a second loading results in a separated case head.:dunno: How can there be that much spring in a case hardened rifle reciever? The case head that hit me fell into my shirt pocket after it hit me in the head and it is about 1/4" long. The remaining case easily came out with a tap with no sticking evident.

Any ideas? I have pondered this for two years, and I find it very suspicious.:slap:

Jim.

I had exactly the same problem with mine, except it happened with new, factory loaded ammo. I alway's assumed it was headspace.

Are you saying the action opens and the case head separates? :mad: (Or equally bad, the case separates and the action opens?):yikes::yikes:

For what it's worth, fire a resized/primed-only case and tell us if/how much the primer backs out.

A fired primer is flush with case head, which was what I expected. Believe me, headspace isn't the problem.:confused:

I don't know what happened other than the case head hit me in the head above my left eye. If you are familiar with Remington Rolling Blocks, once the trigger is pulled and the hammer falls, it is a tight lockup. The hammer is firmly beneath the block, all held together by the pins through the hammer and block. I am puzzled as to how something that large exited between the barrel and the block, when there is essentially zero space between the block and the case head, which is flush with the breech end of the barrel.:dunno:

The action did not open, and can't unless the hammer is pulled to the rear. It had the appearance of a locked breech with smoke coming out of the cracks. With few exceptions, every reload separates just in front of the case head, presumably due to stretch.:yikes:

I use a vernier sight mounted on the receiver buttstock rails, which places my eye in a rearward position. I suspect that sight saved my eye.:bow:

Sounds like someone else had the same experience. If headspace was the problem, I still don't understand how the case head could come out of the locked breech. If you examine a Remington Rolling Block, I think you will see what I mean.:thup:

Jim:cool:

I didn't see you reload data. I shoot a very old RRB (1882) and reload all my ammo.

I didn't see you reload data. I shoot a very old RRB (1882) and reload all my ammo.

I am at work, I will get it for you tonight.

Jim

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Originally Posted by joem

I didn't see you reload data. I shoot a very old RRB (1882) and reload all my ammo.

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By the way, this is a 1902 7mm RRB (smokeless), just for your info.:thup: I do have a Huskavarna (what are the odds of spelling that correctly?), but I have never barrelled it.:dunno:

This was going to be my swamp rifle. I will post a picture of it tonight. I went rather mild on the load, or thought I did. Evidently not mild enough, although factory 7x57 rounds work fine with no problems.:bow:

Jim:cool:

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I don't know what happened other than the case head hit me in the head above my left eye. If you are familiar with Remington Rolling Blocks, once the trigger is pulled and the hammer falls, it is a tight lockup. The hammer is firmly beneath the block, all held together by the pins through the hammer and block. I am puzzled as to how something that large exited between the barrel and the block, when there is essentially zero space between the block and the case head, which is flush with the breech end of the barrel.

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After reading your description, it is my considered opinion that your RRB, and maybe all RRB's are very springy actions. Something is stretching under load.

The original RRB were made for blackpowder, probably made of mallable iron. While the lock up appears tight, that does not mean that the action does not stretch when loaded. Cases developing stretch marks are a dead giveaway that the action is stretching.

While the blocks are large, the load path is through the screws that hold the breech block and the trigger to the receiver. I will bet that those are a mild steel, if that, and the receiver is probably case hardened soft steel.

Cut your loads way down. Heck, use cast bullets, what way you won't be tempted to soup the thing up.

I found your post interesting as it shows that the RRB action does not protect the shooter as well as some other single actions. I suspect a Highwall, Martini Henry, would have protected you better than the rolling block.

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...fired primer is flush with case head, which was what I expected. Believe me, headspace isn't the problem.

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1) But did you fire the primer without a powder charge/bullet -- just empty case?

2) When the case head hit you in the forehead -- but the action was still closed -- did you mean just a piece of the rim?



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Originally Posted by MEHavey

1) But did you fire the primer without a powder charge/bullet -- just empty case?

2) When the case head hit you in the forehead -- but the action was still closed -- did you mean just a piece of the rim?



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Just the primer. I understood what you wanted me to do and why.:super:

This is the rifle.:bow: It is a hoot to shoot, when it doesn't shoot back.:yikes:

Jim:cool:

I didn't answer all your questions.

It was the case head that hit me. I will see if I can find it and photograph it. It is a typical case head separation, about 1/4 inch long. The entire case head. It is not deformed in any way.

I have no idea how it came out, but I have a nice little half moon scar to show for it.

Jim

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Originally Posted by joem

I didn't see you reload data. I shoot a very old RRB (1882) and reload all my ammo.

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The load was 43 grs 4895 and a 130 gr Spitzer with a Winchester LR primer. All cases trimmed to length and full length resized.:super:

Jim:cool:

Something's got to be failing in the lockup.

This will result in the case's forward section/shoulder being anchored by pressure, and the case stretching as it tries to stay engaged with the breechblock face as it opens up. Bang! Instant failure just ahead of the web and the head kicks out-and-up off the inclined breech surface. The hammer (which is still released while you hold the trigger back) then moves forward under its mainspring and closes the breechblock up again faster than the eye can catch it.

There is no other way that much of a cartridge head can physically get out and the action appear still appear closed afterward.

And the only way that the breech can open with the hammer forward is for the circular breech locking cam under the breechblock in the picture/video here to be broken/off (hardly likely), on the edge of misalignment (or at a strange engagement angle), or the hammer/breech pins are somehow failing to keep things in alignment. The cam/engagement mechanism/surfaces are massive, though, and theoretical can't fail.

Have you pulled it apart to look at the pins/cam/block engagement angles after these instances?

http://upload.wikimedia.org/wikipedi...29/M1867_1.jpg

Field Strip a Remington Rolling Block Rifle - Video

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The cam/engagement mechanism/surfaces are massive, though, and theoretical can't fail.

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Somebody would need to model this action and determine what force it takes to force the breech block to override the hammer. Because that is what is happening.

The action is opening. The breech block is forcing the cammed surface of the hammer to move. I suspect there is enough spring in the action for these to occur. The breech block forces that hammer cam back, then the breech block opens, case head comes out, and then the hammer spring pushes the hammer and breech block closed.

You can't see it because it is happening too fast for your perception.

Under load, with a high speed camera, you would see things moving. Actions are not static, under load they stretch and move dynamically.

Disassembly shows no sign of failure or wear. The pins are very tight, lockup appears very secure, and I have found nothing to indicate a failure of any type except for that little scar on my forehead. I have no problems with new cases, but once fired cases are a disaster. They all fail with few exceptions.

I was checking my notes when I was retrieving the load data, and in a 10-shot string of reloads, seven cases failed. Only one has ever caused a problem. None of the case head failures has caused gas to hit me in the face. Most of the case failures are not complete separations.

I "built" the rifle myself, and I did shorten (and re-taper) the barrel by one thread to eliminate any chance of excessive headspace (squared up the end of the barrel and finish reamed the chamber myself). When I finish reamed the chamber, I made one turn of the reamer at a time until the breach block would close on a GO. It has minimal headspace. When the block is in battery, it is actually in physical contact with the barrel face and the case head.

I know something occurred that was different from any other shot. A 1/4" long case head cannot pass between two surfaces less than 0.001" apart. But...for the case head to come out, the block had to be open, the hammer had to be retracted, and both went back into battery.

The only event I can conjure to create this sequence of events is that the hammer recoiled sufficiently to allow the block to move slightly to the rear and allow the case head to escape, but what force moved the block back into battery? THAT is the part that escapes me. The rifle has a thinned trigger spring (ala De Haas), and a primer could conceivably force the firing pin back hard enough to move the hammer, and subsequently the block. I just can't understand what force moved the block back into battery.

Jim

The hammer moved it back into battery, Jim, as you still had the trigger pulled and the sear was disengaged.

Put the full-up/stronger spring back in.

Believe it or not I had a similar problem last week with a S&W Model-19 which had had its mainspring cut down to smooth out the action. Primer setback could then push the hammer to back out enough to allow primer flow right back to/into the firing pin hole and lock up the cylinder on every full-up/40,000psi .357Mag load.

Putting the original mainspring back in solved the problem.

In the Model-19 it was an annoyance. With the rolling block's dependence upon hammer position to lock up the breech, that sounds like a potentially fatal annoyance.

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Originally Posted by slamfire1

Somebody would need to model this action and determine what force it takes to force the breech block to override the hammer. Because that is what is happening.

The action is opening. The breech block is forcing the cammed surface of the hammer to move. I suspect there is enough spring in the action for these to occur. The breech block forces that hammer cam back, then the breech block opens, case head comes out, and then the hammer spring pushes the hammer and breech block closed.

You can't see it because it is happening too fast for your perception.

Under load, with a high speed camera, you would see things moving. Actions are not static, under load they stretch and move dynamically.

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The breach block of a RRB cannot force the hammer back in any way. Once the hammer has progressed to the point where the breach block is above the curvature of the hammer, the block can only move back if the hammer is retracted. There is no cammng surface.:cheers:

Jim

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Originally Posted by slamfire1

Somebody would need to model this action and determine what force it takes to force the breech block to override the hammer. Because that is what is happening.

The action is opening. The breech block is forcing the cammed surface of the hammer to move. I suspect there is enough spring in the action for these to occur. The breech block forces that hammer cam back, then the breech block opens, case head comes out, and then the hammer spring pushes the hammer and breech block closed.

You can't see it because it is happening too fast for your perception.

Under load, with a high speed camera, you would see things moving. Actions are not static, under load they stretch and move dynamically.

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The breach block of a RRB cannot force the hammer back in any way. Once the hammer has progressed to the point where the breach block is above the curvature of the hammer, the block can only move back if the hammer is retracted. There is no cammng surface.:cheers:

Jim:cool:

Well, your data and technique may show why you're getting head separations.

1. That's not really a mild load. Quickload estimates it near 45,000 p.s.i. (and that estimate could be significantly lower than the actual pressure generated in your rifle with your components).

2. If you're full-length resizing in a regular 7x57 die, you're probably producing cartridges with significant end-play, even in a minimum chamber. Remember, it's not the gun's headspace dimension that counts, it's the fit of the case between breechblock and chamber. Many mass-produced dies size for about .006" end-play in a minimum chamber. Ignoring action flex, that's .018" stretch for three firings - an amount close to the failure limit of much commercial brass. Add the flex inherent in the RB action and some cases won't survive two uses.

You can alleviate the stretch by reducing the powder charge to a more moderate level and sizing cases just enough to allow action function, striving for zero end-play. Also, useful 7x57 cases can be formed from heavy .30/06 military brass using your regular sizer and trimmed to length with any common trimmer setup (preferably powered). Such cases have heavier walls than most 7x57 commercial brass and will withstand more stretch.

I suspect that the sequence of events that allowed the case head to escape was -

1. The over-stretched case separated at about peak pressure and moved rearward at high speed, unrestrained by the now-detached case body's friction with the chamber.
2. The primer, as part of the head, struck the firing pin with sufficient force to drive the hammer back enough to clear the breechblock's locking surface. Finger still on trigger kept sear from engaging.
3. Residual pressure could then blow the block open enough to allow the case head to escape.
4. With the case head gone, no internal pressure remained, allowing the hammer spring to return hammer and breechblock to the normal fired position.

https://www.milsurps.com/images/impo...partopen-1.jpg

While this seems a highly unlikely string of unusual events, it's the only way I can imagine the case head could escape unless some part of the action were broken, missing, or deformed.

It's bouncing. I'll bet you'd see the breech almost completely open and then bounce off the bottom back up in a highspeed camera run. It *has* to open near completely if the case head is to get out as you describe.

(If you dare) have someone off to the side with a DSLR on multiframe mode and you under the table as you pull the trigger with a sting/gun sandbagged down. See if you can catch any breech or hammer setback movement.

(Or you can just put the full-up mainstring back in and see if cases still exhibit stretch.)

My thought is that it doesn't open all the way if the case doesn't separate. Once it separates, though, everything opens the rest of the way up. The breech opens/slams back and down all the way, and then bounces back up and the hammer closes it.

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Originally Posted by MEHavey

The hammer moved it back into battery, Jim, as you still had the trigger pulled and the sear was disengaged.

Put the full-up/stronger spring back in.

Believe it or not I had a similar problem last week with a S&W Model-19 which had had its mainspring cut down to smooth out the action. Primer setback could then push the hammer to back out enough to allow primer flow right back to/into the firing pin hole and lock up the cylinder on every full-up/40,000psi .357Mag load.

Putting the original mainspring back in solved the problem.

In the Model-19 it was an annoyance. With the rolling block's dependence upon hammer position to lock up the breech, that sounds like a potentially fatal annoyance.

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Bright minds think alike. I have come to the same conclusion.:) I didn't like the heavy RRB spring at all. I think I will rig up a coil spring setup that is adjustable. Frank De Haas, Mr. Single Shot, had a similar setup in one of his rifles. You get the necessary spring strength without the harsh trigger pull. I am a strong fan of light crisp trigger pulls, but not at the expense of my eyes. :surrender: I was probably a few thousandths of a second from a real disaster. I look funny enough as it is.:madsmile:

I wonder what other problems I have that you guys can solve.:super: This is a neat frum. I thank you all for your input. I bought that first 7mm RRB in Columbus, Mississippi in 1968. I have always regretted selling it.
:crying:

By the way, I am the guy who built the 22 K-Hornet by cutting and shortening a 91 Mauser receiver (posted several months ago). You guys may remember I was having a problem with split cases fireforming the K-Hornets from Remington Hornet brass. From all your posts, I solved that problem. That K-Hornet is fun to shoot, cheap to shoot, and deadly on cottonmouths in the swamp!:yikes:

Thanks, everyone.

Jim :cool:

PS
I have always wanted a Model 19 since I read an article on the Model 19 by Skeeter Skelton (I am old!). I settled for a 3" SS Model 66.:bow: My favorite wheel gun is still my $99.00 (new) 1972 Ruger 45 Colt (4 5/8" barrel - originally 7 1/2" but I cut it and never regretted it) in a Troy Mason hand made holster.

Jim:

The only way for a RRB to do what you describe is for the block to retract (the sear can't engage because you finger is holding the trigger/sear to the rear), the breach to open, the case head to pop out, the breach to close (powered by inertia?) and the the block to fall back to the fired position (finger still holding trigger to rear). The only way to power this sequence is for the firing pin to transfer enough push from the primer/gun powder to the hammer face that it actuates the block.

Check the clearance between your firing pin & firing pin hole. The 7 mm RRBs had a samll dia. firing pin. The black powder RRBs had a firing pin about .1" dia. It may be possible that you have a BP block & firing pin or that you have a BP block & smokeless firing pin. A contributing factor may be a weak mainspring since that is what keeps the block closed. The BP rifles, when converted to smokless rounds could do this. The fix was to bush the firing pin hole & use the smaller dia. firing pins. Remington recognized this problem & that is why the smokeless actions had the small dia. firing pin.

I own a BP RRB & have never experienced this although I use smokless loads almost exclusively. But, it's a .45-70 & pressures are low anyway. I once barreled a 7 mm action in .257 Roberts but kept loads to the 36,000 CUP limit of factory ammo. Again, never had a problem. What pressure level are you loading?

Kirk and Parashooter,

Looks like about 45,000 psi according to Parashooter, and I have faith in his opinions (03 forum). It chronos at 2600 fps. The RRB is a small firing pin smokeless receiver with the correct hammer. I have both BP and 02 smokeless receivers. The pins in this one are ground drill rod and lapped to the pin holes for an exceptionally tight fit with honed trigger engagements. I think everyone has convinced me it is the mainspring. I taper cut the mainspring to lighten that awesome 8 lb trigger pull. I may have overdone it a tad. I will make a coilspring setup for it and report back the results. I will also back off the 43 grs 4895 (twenty year old 4895 BTW). My "screaming meemy" days are over anyway.

I like that idea of using GI brass too. I have an awful lot of LC 54 brass lying around.

I may just reclaim a nice swamp rifle!

Just wait until you see my 7.65mm Arg Swamp Rifle. 5(+) lbs of awesome! I am rust bluing the barrel right now.

Jim

:beerchug:Roger all....

I like the theory that the firing pin is coming back with enough speed to knock the hammer nose out of its locking recess.

A stronger spring would be a good second step, after cutting your loads.

Carbine Williams lives:super: on....

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Originally Posted by slamfire1

I like the theory that the firing pin is coming back with enough speed to knock the hammer nose out of its locking recess.

A stronger spring would be a good second step, after cutting your loads.

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I agree.:super:

Jim:cool:

Shown below is the 7x57 case head that hit me. Note it is undamaged, other than being parted. New case reloaded once.:thdown:

The second case is a 22 K-Hornet case that separated. Too many reloadings me thinks. I have been filling the case with IMR 4520 and seating a 40 gr V-Max, compressing the load (13.5 grs). Not too freaking accuruate. If anyone has a good K-Hornet load for the 40 gr V-Max, I could sure use one.:madsmile:

Jim:cool:

Excuse me, I meant 4227.

Jim

There is a solution to premature head separations in some of our more flexible actions, but since it goes against a popular bit of conventional wisdom, it's considered dangerous heresy by many experienced handloaders - although a few of us have been using it for years with good results.

https://www.milsurps.com/images/impo...dsepcast-1.jpg

Upper case was collet-die neck-sized, reloaded, and fired 10 times in excellent-condition Lithgow SMLE with 180-grain bullet over 41 grains of RL-15 (1 grain under "maximum" per Alliant website data). Case elongated from 2.210" to 2.222" in five shots, was trimmed back to 2.210" and separated on 10th shot. (Case body was stuck so firmly in chamber that chamber cast was needed to remove it - and it still didn't budge until the cast has been driven about 1/4".)

Lower case, from same batch, has been reloaded and fired 15 times with same load in same rifle. Its length has remained at 2.210" - with zero elongation and no internal or external signs of stretch.

The difference? Upper case was kept clean and dry throughout test - lower case received a very thin application of castor oil before each firing.

While it's well-established that lubricated cases allow more force to be transmitted to the bolt face than do dry cases, studies quantifying the difference are rarely cited. According to one impressive-appearing modeling exercise (at Rifle Chamber Finish & Friction Effects on Bolt Load and Case Head Thinning Calculations done with LS-DYNA ) the calculated difference in peak bolt face load between a greased case and a dry case in a smooth chamber is about 10%. If this model is accurate, the difference is barely significant and is in fact less than the normal acceptable variation in peak pressure within a fairly small sample of identical loads.

Whether or not any increased wear on the rifle action resulting from the added load caused by lubricated cases is more important than cartridge case longevity is an individual judgment call. Used with sufficient care (and moderate powder charges), lubed cases can provide a practical alternative to premature separations that may be useful for experienced handloaders who understand the risks and benefits.

Notes: Careful application of thin lubricant coatings should not be confused with the sort of heavy lubrication that can prevent a case neck from expanding and releasing the bullet cleanly - a condition that can produce destructive pressure. Also, oiled cases will collect airborne grit and must be protected from it. An alternative useful in gritty environments is lubrication with a coat of dry wax.

Interesting. I had not considered lubricating the brass. It does remind me of the 1903 issues that arose in the early years.

Jim

I've noticed that many students of US military rifle lore think of the difficulties encountered with the 1921 "tin can" match ammo whenever lubricated cases are discussed. The actual problem with the 1921 ammo was not case lubricant but bullet lubricant inappropriately applied. To quote Hatcher, "If the bullet had been dipped in grease, this generally meant that the neck of the cartridge was greasy too. The space between the neck of the case and the neck of the chamber was filled with an incompressible substance, and the first moderate rise in pressure found it impossible to expand the neck and release the bullet. Thus the powder was strongly confined right at the beginning of its ignition, and accordingly the pressure rose disastrously." (Hatcher's Notebook, p 341).

As described by Hatcher, this problem was quite distinct from the added breech thrust occurring when the case body is lightly lubed. Although careless application of excessive case body lube could certainly have the same effect, such a result is easily avoided by applying only a very thin film. I like castor oil for this because it's cheap, super-slick, easily applied, and viscous enough not to run where it isn't wanted. I've never tried the paste-wax approach, but reports from others indicate it's effective (and doesn't collect grit).

Was was that chamber cast made of - lead?

Jim

Cerrosafe.

Lubricated cartridges case myth started with “Hatcher's Notebook” and his section on the 1921 Tin Can ammo. The tin on the bullet jacket cold welded the bullet to the case neck. This created a bore obstruction. A number of rifles were ruined at the National Matches. The Ordnance Department who supplied the ammo, decided to shift the blame to the shooters by blaming an operational practice of the shooters.

They found a unique practice at the time, shooter’s were greasing their bullets to reduce copper fouling. Ordnance claimed that was the reason the rifles blew up. They concocted reasonable sounding theories (all ignoring the bore obstructions that cold welding created) and ran rigged pressure tests to prove their case. Greased bullets were banned for more than 50 years at the National Matches until the original reason was forgotten.

I think the millions of Moly Lubed bullets fired down range have somehow proved the Ordnance theories and tests as bogus. Being a loyal Ordnance Officer, Hatcher reported the theories and failure analysis uncritically. Somehow people reading his book did not see the inconsistencies, and confused greased bullets with case lubrication. This confusion was codified, repeated as fact, time and time again by Gunwriters of the 1970’s and has become a “cultural memory” in the reloading community.

No action is designed assuming that the case provides any friction or carries any load. Take a look at the calculations on Lija’s page and at the article bolt lug strength. Lilja Precision Rifle Barrels - Articles: A Look at Bolt Lug Strength.


I highly recommend visiting the above referenced site and seeing a dynamic analysis of chamber finish/case fricition. Rifle Chamber Finish & Friction Effects on Bolt Load and Case Head Thinning Calculations done with LS-DYNA What I want to point out is that as case friction is reduced, case stretch is reduced. If this is true, it may mean that that cases are less likely to rupture, either through a brass flaw, or through repeated firing, if the cases are lubricated.

The lubricated cartridges case myth started with “Hatcher's Notebook” and his section on the 1921 Tin Can ammo. The tin on the bullet jacket cold welded the bullet to the case neck. This created a bore obstruction. A number of rifles were ruined at the National Matches. The Ordnance Department who supplied the ammo, decided to shift the blame to the shooters by blaming an operational practice of the shooters.

Shooter’s were greasing their bullets to reduce copper fouling. Ordnance claimed that was the reason the rifles blew up. They concocted reasonable sounding theories (all ignoring the bore obstructions that cold welding created) and ran rigged pressure tests to prove their case. Greased bullets were banned for more than 50 years at the National Matches until the original reason was forgotten.

I think the millions of Moly Lubed bullets fired down range have somehow proved the Ordnance theories and tests as bogus. Being a loyal Ordnance Officer, Hatcher reported the theories and failure analysis uncritically. Somehow people reading his book did not see the inconsistencies, and confused greased bullets with case lubrication. This confusion was codified, repeated as fact, time and time again by Gunwriters of the 1970’s and has become a “cultural memory” in the reloading community.

No action is designed assuming that the case provides any friction or carries any load. Take a look at the calculations on Lija’s page and at the article bolt lug strength. Lilja Precision Rifle Barrels - Articles: A Look at Bolt Lug Strength.


I highly recommend visiting the above referenced site and seeing a dynamic analysis of chamber finish/case fricition. [url="http://www.varmintal.com/a243z.htm"]Rifle Chamber Finish & Friction Effects on Bolt Load and Case Head Thinning Calculations done with LS-DYNA

What I want to point out is that as case friction is reduced, case stretch is reduced. If this is true, it may mean that that cases are less likely to rupture, either through a brass flaw, or through repeated firing, if the cases are lubricated.

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Notes: Careful application of thin lubricant coatings should not be confused with the sort of heavy lubrication that can prevent a case neck from expanding and releasing the bullet cleanly - a condition that can produce destructive pressure. Also, oiled cases will collect airborne grit and must be protected from it. An alternative useful in gritty environments is lubrication with a coat of dry wax

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I used "stick wax" to coat almost 1000 CAVIM 308 cases. It was a bad idea as "stick wax" is thick and just impossible to wipe off. So I shot the stuff in a FAL :madsmile: The stick wax was on thick and greasey . As I was able to dial down the gas port and have the rifle still function, I know the wax coating reduced breech friction. I did not have any pressure problems. I think as the case neck opens up, any grease or what not is squeezed out to the breech end. The case neck expands first, then the thicker parts of the case after that.

Question: Why would not residual case lube (after a cursory wiping down with rag to remove gross excess) perform the same function as carnuba wax/castor oil, etc?

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  Originally Posted by MEHavey

  Question: Why would not residual case lube (after a cursory wiping down with rag to remove gross excess) perform the same function as carnuba wax/castor oil, etc?

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It does. However, neck-sizing with a collet-style die requires no sizing lube, so if lube is elected for firing it has to be added. If F.L. sizing, I can't imagine using so much lube that a wipedown (cursory or otherwise) would be needed - unless one is enamored of lube dents in one's sized cases.

Personally, I stopped removing sizing lube years ago (unless I'm expecting exposure to grit - or loading .22 Jet revolver ammo). My cases last longer and I save the annoyance of cleaning off lube. Still, this is not a technique for novices or those without a solid understanding of the principles and details involved.

Right. (And since I'm a Redding bushing die fan, you gotta point there.)

Has anyone heard of a rolling block discharging when the block is closed? (A stuck firing pin that hits the primer.) I had heard this some where. I always close the block slowly on my '67 danish in 50-70 when I shoot it.
john

I've not heard of it happening but I do recall reading that the the firing pin can freeze in place. Some guns were made with no means to retract the firming pin; some were made with coil springs around the firing pin & some have a cam that retracts the firing pin as the block is opened. See DeHass' Single Shot Rifles & Actions.

DeHass's book is excellent, and well worth the price for single shot fans.

Jim

This is an interesting thread. I have 2 comments to add.
A friend of mine had one of the 7mm RRBs. He loaded and fired a single round which blew the breech open. The expanded case was left in the barrel and the primer was impaled on the firing pin in the open the breech block. He took his damaged case back to the gun shop and they produced a 7X57 case they had fired that looked normal. I know the shop well. They are honest but not particularly special gunsmiths.
My friend checked his chamber with a cast and showed it to me. The casting showed the chamber had a slightly shorter neck and sharper shoulder than a normal 7X57 case.
When his cartridge was fired he theorized that the heavy hammer blow drove the case mouth in to the throat causing the high pressure and pierced primer. The pierced primer blew the hammer back and the residual pressure opened the breech block. This may offer a clue to how the breech block opens. A high pressure gas leak may be able to blow the hammer back. It sure blew his open though his primer was pierced to enable it.

In regard to oiled cases. I had read of lightly oiled brass fire forming and stretching less and I began trying it with a 40-65 High Wall. This is low pressure ammo in a massively strong action. The case fire formed well and there were no issues. Next I tried a CZ 527 in .22 Hornet. Then reformed .303 WW and R-P brass in a 6.5X53R Dutch M95 Steyr Mannlicher rifle. The cases fire formed perfectly. Since then I have made it a practice wipe a very thin film of oil on each case as I fire form new brass. All my experience with this had been positive.
I don't plan using this for normal shooting of fire formed brass in a rigid bolt action. For this application it only slows down shooting as my existing brass life is nearly infinite with failures being neck or body splits. I will definitely use this technique to prolong case life in the springy Lee-Enfield rifles and reduce the extraction load on my Hakim extractor.

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A high pressure gas leak may be able to blow the hammer back. It sure blew his open though his primer was pierced to enable it.

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I absolutely believe that a pierced primer could vent through the firing pin hole and unlock the hammer.

I recall firing Iraqi Ball in a 303 British rifle. The stuff I had was awful, over pressure and it pierced primers. The gas venting would blow the firing pin all the way back. I had to remember to place my thumb out of the way as the cocking piece snapped hard.

Then I had some awful 8 mm ammo. That pierced primers and blew the firing pin back.

If pierced primers can blow a firing pin back to the stops under spring tension, I have no doubt that it could unlock the hammer.

Incidentally, last weekend I shot some 30-06 in a push feed rifle. I was shooting 169 Lapua with 48 grains of Pat's surplus AA2520. This lot of powder is one grain slower than the other AA2520 I have had. The first five shots all had case head separations. It was my reloads, and I figured I had oversized the cases (Which proved true when I got home and measured loaded ammo.) So, I got out a bottle of 10W-30 and coated the remaining cases with oil. Fired twelve more rounds. One round had a case head separation mark. Eleven rounds did not.

Funny thing is, the groups with oiled cases are tighter. Significantly better clusters.:madsmile:

From looking at an exploded view of the action parts, The block is only secured by the hammer on firing. If the hammer spring is weak, it can allow the action to open under pressure. The action would close again as the pressure returns to normal. This would happen very quickly, giving the impression that the action remained closed. The use of a reload with the slightest amount of sizing lube on the case would add to the problem. That is why the factory ammo works OK.
Compare the spring strength to your other action and check the cases for sizing lube.

The RRB is a self locking action. That is as the hammer rolls under the breech block it locks and any firing forces create more friction that helps keep it locked. However if a huge gas leak blows back against the hammer the gun may unlock as the pressure drops.

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Originally Posted by ireload2

This is an interesting thread. I have 2 comments to add.
A friend of mine had one of the 7mm RRBs. He loaded and fired a single round which blew the breech open. The expanded case was left in the barrel and the primer was impaled on the firing pin in the open the breech block. He took his damaged case back to the gun shop and they produced a 7X57 case they had fired that looked normal. I know the shop well. They are honest but not particularly special gunsmiths.
My friend checked his chamber with a cast and showed it to me. The casting showed the chamber had a slightly shorter neck and sharper shoulder than a normal 7X57 case.
When his cartridge was fired he theorized that the heavy hammer blow drove the case mouth in to the throat causing the high pressure and pierced primer. The pierced primer blew the hammer back and the residual pressure opened the breech block. This may offer a clue to how the breech block opens. A high pressure gas leak may be able to blow the hammer back. It sure blew his open though his primer was pierced to enable it.

In regard to oiled cases. I had read of lightly oiled brass fire forming and stretching less and I began trying it with a 40-65 High Wall. This is low pressure ammo in a massively strong action. The case fire formed well and there were no issues. Next I tried a CZ 527 in .22 Hornet. Then reformed .303 WW and R-P brass in a 6.5X53R Dutch M95 Steyr Mannlicher rifle. The cases fire formed perfectly. Since then I have made it a practice wipe a very thin film of oil on each case as I fire form new brass. All my experience with this had been positive.
I don't plan using this for normal shooting of fire formed brass in a rigid bolt action. For this application it only slows down shooting as my existing brass life is nearly infinite with failures being neck or body splits. I will definitely use this technique to prolong case life in the springy Lee-Enfield rifles and reduce the extraction load on my Hakim extractor.

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My chamber neck is short also.:confused: I trim the cases about 1/16" to avoid an unsightly ring around the fired cases. I cut my own chamber with a reamer I bought off eBay. I have refused to sell it even though I now have no use for it because I think it is improperly ground (brand name reamer too).:dunno:

My problem was a very light mainspring that I thinned to reduce that awesome RRB trigger pull. It would appear I went too far.:eek: Trigger pull is great, but evidently the recoil of the firing pin is forcing the hammer back and opening the block. I have experienced no pierced primers. That picture if the blown case is the actual case head that hit me above my left eye. It was not a light blow. I found it in my shirt pocket after I got home. The blown case came right out with no problem.:cheers:

I am now trying to perfect a coil spring setup (ala DeHass) to stop the breech block from opening and simultaneously improve trigger pull.:super:

Oiled cases make me nervous. I will try that as a last resort. I think I read Hatcher too many times. This is a plot of 1903 Failures I deveoped from Hatcher's and SRS data. The receiver failures have a yellow center. A lot of those failures were attributed to greased rounds.:slap:

Jim:cool:

Jim, I believe the "greased round" problem was the fact that the troops would slather grease on the bullet/neck of the case. At that point the neck/chamber clearances were hydraulically reduced to "zero," the neck could not expand to release the bullet, and the rest (was) history.

Do a little Googling and see if you read it the same way....

MEH,

I do read it the same way. I used to know the name of the grease they used, and it was heavy grease vs oil.

Will glycerin work?

Jim

Jim:

Before I reload a case, I tumble clean them. They come out, in addition to being clean & bright, with a very slight coating of case cleaner (I use the Midway brand) & feel "slick". There is no discernable residue, nothing to come off & building up in the neck or leade, just a polished, slick surface on the case. I believe this promotes good feeding through the mnagazine, especially in semi-autos like the Garand & AR15.

Jim, I see you're still "barking up the tree the squirrel ain't in". One more try to explain the difference between a heavily greased case neck and a lightly oiled case body -

• Heavy grease on case neck can prevent neck from expanding to release bullet cleanly. This increases chamber pressure.
• Light lube on case body inhibits adhesion of case walls to chamber. This increases thrust delivered to breech block or bolt face but doesn't significantly affect chamber pressure.
• Heavy lube on the whole deal can increase both thrust and pressure.

For an entertaining narrative on the greased neck problem, see Dick Culver's article at http://www.odcmp.org/1101/can.pdf

Dick Culver merely regurgitated (though in an interesting fashion) the data from Hatcher's Notebook. Which I believe is suspect.

The first problem I have is that the test "proves" that a carefully greased bullet creates an overpressure condition. This would mean that putting moly on bullets increases pressures. Recent data indicates that this is not true.

The second problem I have is that the Ordnance Department is the one conducting the tests. They are not an independent or objective tester. History is replete with examples of what happens when an agency, such as a Police Agency, conducts a test to prove a desired outcome. You can turn on the television and find lots of shows where people were exonerated after the Police tests were found to be bad science at best, and at worst, fabricated to prove the Government case.

(Any one remember all the evidence for those "Weapons of Mass Destruction" we were supposed to find?)

In this case, the Ordnance Department was looking to pass the blame of cracked receivers to the civilian shooters. They ran a test, found the data they were looking for, and bingo! Civilians and their greased bullets were the cause. The cold welding issue was sort of a secondary, barely important, most unfortunate thing.

But it was the cold welding that dangerously raised pressures by creating a bore obstruction.

I believe that the Ordnance Department had an instrumentation issue. Their crusher guns were highly sensitive to frictional changes on the crusher piston. (Phil Sharpe discusses this) I have read nothing investigating whether grease getting into the piston changed the crusher reading. I believe this is what caused their high reads on the “lightly greased” bullets.

As for the catastrophic pressure rises, how do I know it was not a cold welded tin can bullet?

I am skeptical about grease preventing expansion of the case neck. At least in a tapered bottle neck cartridge. The first thing to expand is the case neck. It is the thinnest part of the case. Having fired cases coated in stick wax, the cases I examined later showed normal case neck expansion. I believe that as the front of the case expands, the stick wax was squeezed out towards the base.

Slamfire:

"Greased" neck/bullet is far different from a (very) slight residual coating of wax/sizing lube. Like you, I have found the latter to increase case life considerably (factors of 2-4 in some cases -- no pun intended).

The "grease" problem, however, was just that -- grease. Soldiers/competitors would literally dip the bullet into grease and chamber the round. Guess where the excess grease went as the round entered the throat? Bingo: Instant custom-fit/hydraulic/zero clearance in the neck area.

Bad juju.

Quote:

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Originally Posted by MEHavey

Slamfire:

"Greased" neck/bullet is far different from a (very) slight residual coating of wax/sizing lube. Like you, I have found the latter to increase case life considerably (factors of 2-4 in some cases -- no pun intended).

The "grease" problem, however, was just that -- grease. Soldiers/competitors would literally dip the bullet into grease and chamber the round. Guess where the excess grease went as the round entered the throat? Bingo: Instant custom-fit/hydraulic/zero clearance in the neck area.

Bad juju.

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MEHavey: I know the theory sounds good, I also know I have done some stupid stuff and survived.

One of those idiot events was dropping globs of stick wax in a plastic bag along with a case of factory CAVIM ammo. I rolled the cases around till they were well coated with stick wax. Stick wax is horrible stuff, far "sticker” and ‘waxier” than axle grease.

I fired most of that ammo in an Argentine barreled FAL

https://www.milsurps.com/images/impo...DSCN4741-1.jpg

Some of the ammo I wiped the stick wax to a thin coating. I got tired of this and loaded many magazines full of greased gobbed ammo. And fired it. The effect was immediate. Breech friction was significantly reduced. I was able to turn the gas port down a lot, and the rifle functioned every round. It functioned well below the minimum gas port setting required for dry ammo. Also, stick wax just coated the areas inside the magazine, bolt face, and breech end.

I am not going to try to fill a barrel with grease and see what happens. But based on my experience with heavily greased cartridges, I don’t believe any of the conclusions reported by Hatcher.

As noted, shooters had been using axle grease for years. It was only until the tin coated bullets created a bore obstruction, that the military in a buck passing exercise, banned the grease. And ignored cold soldering as the source of receiver cracks.

And ignored that most of the receivers on the line in 1922 were single heat treat some with burnt receivers. Stuff they had made.

The Army was not responsible for any of it: Nope, it was all the civilians fault.

Both armories went to DHT or nickel steel in 1918. There were no SHT receivers on the line in 1922.

Jim

Quote:

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It was only until the tin coated bullets created a bore obstruction, that the military in a buck-passing exercise, banned the grease.

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See:
The Hunter's Guide to Ballistics ... - Google Book Search
also...
http://www.cruffler.com/trivia-January01.html

I agree with you that the cold-solder problem with the early FMJ bullets was the gorilla in the living room for pressure/spike failures; and I have a problem seeing the difference between tumbled/mirror-shined cases giving the bolt face all that much more thrust that ones w/ a "little" resizing lube residual upon firing.

But I ain't gonna dip my bullets into axle grease any time soon. :madsmile:

>>>I have a problem seeing the difference between tumbled/mirror-shined cases giving the bolt face all that much more thrust that ones w/ a "little" resizing lube residual upon firing.<<<

The number of variables that can exist given mirror polished brass, highly polished chambers, a little lube left on the brass and residual lube not wipe from the chamber after cleaning make the entire process some what unpredictable.
People seem to think they can get something of technical value using the walls or the case body as something of a "mechanical brake" takeing a load of of the bolt face. It is a laughable notion. With a case head separation there is zero remianing "mechanical brake", no friction nothing. In addition the entire face of the breech or bolt is subjected to the escaping chamber pressure. Rather than depend on the case walls which also vary in thickness, temper, strength and quality the design needs to be robust.

Quote:

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Originally Posted by ireload2

>>>I have a problem seeing the difference between tumbled/mirror-shined cases giving the bolt face all that much more thrust that ones w/ a "little" resizing lube residual upon firing.<<<

The number of variables that can exist given mirror polished brass, highly polished chambers, a little lube left on the brass and residual lube not wipe from the chamber after cleaning make the entire process some what unpredictable.
People seem to think they can get something of technical value using the walls or the case body as something of a "mechanical brake" takeing a load of of the bolt face. It is a laughable notion. With a case head separation there is zero remianing "mechanical brake", no friction nothing. In addition the entire face of the breech or bolt is subjected to the escaping chamber pressure. Rather than depend on the case walls which also vary in thickness, temper, strength and quality the design needs to be robust.

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You might find Parker Ackley's tests interesting. I can't remember if it was a Winchester or a Marlin lever action, but he cut off the bolt restraints and fired a round with no damage to the rifle, and the bolt didn't even open. I think it was a 30-30, but not certain.:D

According to tests by Ackley, straight walled cases (improved) impart less bolt thrust than bottleneck cases.:thup:

I have no dog in this hunt, I just thought you might find the tests interesting. The tests ae written up in one of his reloading manuals.:beerchug:

Jim:cool:

Quote:

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Originally Posted by Jim Tarleton

Both armories went to DHT or nickel steel in 1918. There were no SHT receivers on the line in 1922.

Jim

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I do have rationale to support a position that this is probably not accurate.

We really should take this up in the 03 Forum, as this thread is not even in the same Solar System as the first post.

>>>You might find Parker Ackley's tests interesting. I can't remember if it was a Winchester or a Marlin lever action, but he cut off the bolt restraints and fired a round with no damage to the rifle, and the bolt didn't even open. I think it was a 30-30, but not certain.<<<<

I have read Ackley's test. I am sure you can find a way to make that happen.
However they put locking lugs on bolt for a reason. Other wise the hammer could just hit the back of the cartridge with no rolling block required.

I agree wholeheartedly.

Jim