Case Head Exits Rifle

[Parashooter]

Cerrosafe.

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[slamfire1]

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.

[slamfire1]

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.

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

.

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 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.