Cases and Enfields and lube - Oh my!

[Edward Horton]

If you take the time to do some simple math with the figures below in blue you will see that there is approximately a 40% increase in bolt thrust with an oiled or greased cartridge. (Forgive me I rounded up, the actual figure from U.S.Military is 39.21568 % increase in pressure or bolt thrust.)

I keep furnishing data for you all to look at and you keep ignoring what I post and then complain I’m just parroting a bunch of garbage or what I’m posting isn’t useful. This information was first published in 1921 by the U.S. Military BUT the people who advocate greasing their cartridge cases seem to want to overlook this piece of vital information.

Then I ask myself why other people can’t figure out that an oiled or greased case adds 40% to you pressure or bolt thrust figures with all the data and information I have provided. The only difference between the 30-06 and .303 British is the .303 British is .010 smaller in base diameter and the pressure-bolt thrust figures would be very slightly less. (it might even drop to 39.2XXXX)

The real question here is do we believe the testing done at Springfield Armory and Frankford Arsenal or do we believe the people who say its safe to grease your cases.

And don’t tell me what Dick Culver wrote here is garbage or doesn’t apply to this subject.

When the "Tin Can" Changed History
By Dick Culver


While the 1920 NM Ammunition was accurate, it was still using a standard cupro-nickel jacketed bullet, although of the same 170 flat-based design as the 1921 projectile. The shooters of course, were solving the fouling problem with liberal applications of grease. Experiments at Springfield and Frankford disclosed that the 1920 NM Ammunition fired in a dry chamber gave approximately 51,000 psi, well within normal specifications. By carefully lubricating the bullet and case neck, the pressures rose to 59,000 psi. When the entire case was lubricated along with the chamber which was common (if unintended) when the cartridges were used in rapid-fire strings, the chamber pressure rose to a dangerous 71,000+ psi, the pressure normally attributed to a proof test load.

Physics and the Rifle Shooter

The inadvertently lubricated cartridge case was the worst problem as its sides were tapered. Normal ammunition forms a gas seal in the chamber due to a process known as obturation. Obturation is simply the expansion of the brass case, tightly sealing the chamber when the round is fired. This case expansion forces little fingers of brass to occupy unseen microscopic irregularities in the chamber walls. This is truly a good thing as it seals the chamber until the gas pressure has subsided. Unsealed chambers allow gas to blow back into the receiver, possibly injuring the shooter. The greasy cartridge case in a tapered chamber had two disastrous consequences. First, grease is incompressible and will not allow the case to expand
within the chamber as it was meant to do. Since the grease decreases the coefficient of friction and allows the cartridge case to slide in and out of the chamber more easily it precipitates what I call "the watermelon seed effect". This equates to the squeezing a fresh, wet watermelon seed between your fingers and having it squirt out into the grass. The greased, (and tapered) chamber has much the same effect on a brass cartridge case. Since the lack of compressibility of the grease prevents the case from expanding against the chamber walls and thus sealing the gas with normal obturation, the tapered case "squirts" to the rear with virtually all of the force of the combustion gasses being directed straight rearward against the bolt.

[Surpmil]

I'm having visions of a appliance that holds a No4 action 'in battery' while a hydraulic piston with a projection the diameter of a bolt and a simple captive firing pin, that will precisely measure the rearward thrust generated by various cartridges, dry and lubricated...

It would be interesting to have exact figures, but of course that would only be half the equation

The other half being what the action can stand, both over the short and longer term.

Fortunately we have real world experience to substitute for such experimentation, and allowing for all the various loadings, every possible permutation of wet, oil, case lube, grease, wrong powders, over-charged cases etc. etc. in the hands of hundreds of thousands of shooters of all levels of skill or incompetency. Do we yet have a single catastrophic failure, after 60 odd years of trying?

[jmoore]

I'm having visions of a appliance that holds a No4 action 'in battery' while a hydraulic piston with a projection the diameter of a bolt and a simple captive firing pin, that will precisely measure the rearward thrust generated by various cartridges, dry and lubricated...

Don't even need a No.4 action to do that test, if all you're trying to do is read the rearward thrust. The "device" would need a very fast pickup to read the peak load though, as it only lasts 0.001-0.002 seconds!

[Edward Horton]

Don't even need a No.4 action to do that test, if all you're trying to do is read the rearward thrust. The "device" would need a very fast pickup to read the peak load though, as it only lasts 0.001-0.002 seconds!

Or find a Excel program set up to give bolt thrust figures, you higher math types can take your shoes off if you run out of fingers and check these figures jmoore you should put in for leave and not cross check these figures at work and get paid for it.

From what I see the proof and bolt thrust figures are CIP pressure standards and not American SAAMI pressure standards.

[slamfire1]

The real question here is do we believe the testing done at Springfield Armory and Frankford Arsenal or do we believe the people who say its safe to grease your cases.

And don’t tell me what Dick Culver wrote here is garbage or doesn’t apply to this subject.

When the "Tin Can" Changed History
By Dick Culver

You are close to the ground zero myth of Lubricated cases. It all started in with tin can bullets issued in the 1921 National matches. Army Ordnance made ammunition with tin plated bullets, which were then fired in single heat treat receivers.

For decades previous shooters had been lubricating their bullets to reduce bore fouling. But suddenly, with the tin bullets, reports are coming out of busted rifles.

Remember Rule #2 of the Government: Avoid scandal. This ammunition was made by Ordnance, the unsafe at any speed single heat treat receivers were made by Army Ordnance, scandal was brewing and scandal will ruin careers. There were some highly placed people trying to find a non service culprit.

Retired head of Army Ordnace Major General J.S. Hatcher writes this up in one page of his book ‘Hatcher’s Notebook” almost 30 years after the events. Maybe forty years. This one page is Ground Zero of the myth.

In 1921, the Ordinance Department conducted experiments to prove that greased bullets caused the blowups. A reading of Hatcher’s book shows that the Ordinance Department totally ignored the cold soldering of the tin plated bullet to the brass case necks of the as a contributor.

Hatcher reported this uncritically. He totally ignored evidence that cold soldering was the primary problem. Remember reading his paragraph when a NCO showed him a case neck and shoulder attached to a tin can bullet? The whole of which had been fired in a rifle, and the case had ripped off below the shoulder. That should have been proof positive of cold soldering, that cold soldering was creating a bore obstruction. But to Hatcher, it was just proof of high pressure caused by those darn civilians greasing their bullets.

If you read “Handloader’s Manual”, published 1937, author Earl Naramore, page 158, you come across this section:

The ammunition made a Frankford Arsenal for the 1921 National Matches had bullets heavily plated with tin. This ammunition was satisfactory when first loaded. Tin has an affinity for brass and in this ammunition the tin combine with the insides of the case necks, forming a union between the bullet and the case just as though the bullets were soldered in place. This union is so strong that it is impossible to extract the bullets and if the ammunition is fired, dangerous pressures will develop. Most of this lot of ammunition, the only one so loaded, has been shot or destroyed, but anyone running across any of it should destroy it or preserve it only as a curiosity in the development of ammunition . It should be under no circumstances be fired. The markings on the case heads is, F.A. 21-R.

You would think Hatcher would have been aware of this, as on the frontpiece of the book, Lt Col. Julian S. Hatcher is given credit for the book sketches.!

At least five M1903’s were blown after the 1921 matches up with FA 21R. Three were double heat treat rifles and two were single heat treat. You would think Hatcher would have been aware of this as these incidents are recorded in his book!

We owe Hatcher a lot. However you do not get to be a Major General, and you don’t get free bee’s from your old organization , by pointing out the stupidity of the Army. In all of his writings, back to the 20’s, Hatcher is 100% pro Ordnance Department. Right or wrong, 100% positive about the Ordnance Department. He is never critical of it at all.

I would think that the millons of moly lube bullets fired quite safely sort of prove that the 1921 tests were bogus and Hatcher’s reporting that greased bullets were dangerous a consequence of selective memory.

So how did these high pressures get created? I believe it is due to instrumentation error and the lack of an independent tester.

Phil Sharpe, in his book Complete Guide to Handloading, discusses how friction sensitive was the period pressure testing equipment.

What I believe happened was that grease was blown around inside their copper crusher pressure testing equipment giving false readings. But the Ordnance testers were under pressure from their bosses to create favorable results, once they got the results they were looking for they went no further. The Army was able to blame the darned civilians, greased bullets were banned, and that was that.

I believe this is an example of what happens when you don’t have an independent tester. When organizations own the testers, the test individuals are under pressure to prove organizational theories. This is a problem common to Forensic crime labs which are particularly helpful in finding results favorable for their fellow law enforcement buddies.*

Everyone involved in these tests died decades ago. All we have are a few writings from dead people, and the expanded misguided theories of Gunwriters from the 60's, 70's, 80's, and 90's. These guys expanded greased bullets to greased anything.

Such as what Dick Culver is doing. Just repeating folk lore and myths around and around and around.

*
“Forensic science” is chock full of similar behaviors. These criminal investigators have sent hundred of thousands to prison, probably thousands to death row, based on nothing more than their community legends. For example, Bullet matching Weak Forensic Science Has High Cost | Amstat News, bullet matching | Center for Investigative Reporting and fire forensic evidence.
http://www.dallasnews.com/sharedcont...n.3fec5f4.html
Cameron Todd Willingham, Texas, and the death penalty : The New Yorker
Man executed on disproved forensics - chicagotribune.com

[Parashooter]

Come on, Ed, that spreadsheet is just a table of industry standards and some calculated results, not test data. The "Bolt thrust wet" column is "Bolt thrust dry" plus 40%. Doesn't take much arithmetic to figure that one. But what is the basis for the 40% assumption? You state you're taking that from the "Tin Can" article. OK, but that refers to chamber pressure, not bolt thrust, and the lubricant used was a fairly heavy grease ("vaseline" per the section of Hatcher's Notebook - Ch. XIV - in which the same numbers appear). How much of the increase in chamber pressure was due to hydraulic lock on the bullet - something that doesn't occur with light coatings of less-viscous lubricant? Would the results show a 40% increase if the cartridges were very lightly oiled instead of more generously greased?

I've fired and chronographed enough lightly-lubed cartridges to be reasonably confident chamber pressures aren't jumping 40% compared to dry ammo. Let's be realistic, the "pressure signs" observable after a 49,000 psi shot are different from those seen after a 68,000 psi shot. It would be hard to miss that kind of increase.

On the other hand, my own primitive calculations (which you can see at post #3 on this thread) seem to show that a 40% difference in bolt thrust, given the same chamber pressure, is a worst-case possibility if the dry case were to be stretched as much as possible without breaking. I don't think we get that much difference when the dry case is not being stretched - the condition we find if we employ some means of eliminating cartridge end-play ("air gap") on firing - but I certainly don't know this for sure.

I started this thread in the hope that we could all work together to find some better answers to these questions on lubed ammo, case life, and possible adverse effects. Your initial reply (post #2) looked like you were interested in learning more also. I would really welcome your help.

[Edward Horton]

I’m not in this posting to help anyone spread the myth its OK the lube your ammo.

The fact of the matter is no one in these forums has the test equipment, strain gauges and pressure measuring gear to ever come to any conclusions.

The facts about lubing cases are already in print.

The myth about it being safe to lube cases is nothing more than a unscientific WAG.

On top of this with the o-ring method of fire forming cases no one needs to even think about lubing a single cartridge case.

How many warnings to NOT lube your ammo do I have to post to get the point across.

[slamfire1]

But what is the basis for the 40% assumption?

Yes, just how much breech friction is the gun designer to assume?

Lets assume breech friction runs from 0 to 100%. Pick a number, what percentage of breech friction, and thus load, is the designer supposed to basis his action on.

0% breech friction, and thus 100% load, or 100% case friction and 0% load?.

And who said that cartridges have to have long sidewalls or the action will be overstretched?

How much of the increase in chamber pressure was due to hydraulic lock on the bullet - something that doesn't occur with light coatings of less-viscous lubricant?

I don't believe in that theory. Based on my horrible stick wax experience, I am confident that any grease or wax is squeezed out of the case neck area of the chamber. Case necks expand first, pushing the grease out of the way.

Incidentally, Hatcher's greased bullets test was conducted with Tin Can ammo. The Army created a bore obstruction by cold soldering, tested the stuff, and blamed the high pressures on those darn civilians and their grease pots.

Which had not caused any problems since 1903.

[slamfire1]

Where are these numbers coming from?

If I take the largest base measurement of the .223 Rem,which is the rim width, which is .378"

And I do the Pie R squared calculation I get

for the SAAMI CUP of 52K a bolt load of 5835 pounds
Sammi Piezo at 55 K a bolt load of 6172 pounds
CIPT at 62K a bolt load of 6957 pounds
And the proof load of 77,900 psia a bolt load of 8742

How the heck is anyone calculating a "wet" bolt thrust of 9647 pounds?

[Edward Horton]

Where are these numbers coming from?

If I take the largest base measurement of the .223 Rem,which is the rim width, which is .378"

And I do the Pie R squared calculation I get

for the SAAMI CUP of 52K a bolt load of 5835 pounds
Sammi Piezo at 55 K a bolt load of 6172 pounds
CIPT at 62K a bolt load of 6957 pounds
And the proof load of 77,900 psia a bolt load of 8742

How the heck is anyone calculating a "wet" bolt thrust of 9647 pounds?

You don't measure the outside diameter of a hydraulic actuator to get the surface area of the piston INSIDE the cylinder. Did you ever notice when using military cases the warning to reduce your powder charge because the case has less internal volume. This means military cases also produce less bolt thrust because the "piston" has less surface area.