Case Head Exits Rifle

[MEHavey]

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.

[Jim Tarleton]

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.

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. I was probably a few thousandths of a second from a real disaster. I look funny enough as it is.

I wonder what other problems I have that you guys can solve. 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.


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!

Thanks, everyone.

Jim

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. 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.

[Kirk]

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?

[Jim Tarleton]

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

[MEHavey]

Roger all....

[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.

[MEHavey]

Carbine Williams lives on....

[Jim Tarleton]

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.

I agree.

Jim

[Jim Tarleton]

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

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.

Jim

[Jim Tarleton]

Excuse me, I meant 4227.

Jim