Case Head Exits Rifle

[Kirk]

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.

[Parashooter]

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

[slamfire1]

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.

[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.

[slamfire1]

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.

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



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.

[Jim Tarleton]

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

Jim

[MEHavey]

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

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.

[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.

[Jim Tarleton]

>>>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.

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.

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

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.

Jim

[slamfire1]

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

Jim

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.