Powder/primer Shelf Life - Page 2

Art Eatman · June 27, 2006, 11:10 PM

I inherited my father's .220 Swift and a bunch of ammo. From the benchrest, I get just inside one MOA. The ammo was loaded in 1969. It worked on prairie dogs, a couple of weeks back.

I've shot some 1968 .243 stuff I'd loaded; same old 3/4 MOA, but point of impact a bit lower than new stuff.

I have some steel-cased .45ACP, EC 43 headstamp, that shoots just fine.

Art

Smokey Joe · June 28, 2006, 12:36 AM

Mike Irwin--I stand corrected. Did a little more checking after seeing yr post. I was wrong, it IS the Potassium Chlorate, not the mercury, that brings about the rusting, just as you said. And the mercury attacks the brass.

You are right, I acknowledge.

JNewell · June 28, 2006, 08:16 PM

Quote:

Mercury compounds attack brass, weakening it, but do not cause rusting.

Does that account for the occasional weakened or through-and-through corrosion I've found in CMP LC .30-06???

**Mike Irwin** · June 29, 2006, 12:01 AM

"Does that account for the occasional weakened or through-and-through corrosion I've found in CMP LC .30-06???"

No.

By the time the .30-06 entered service, mercuric primed ammunition was pretty much a thing of the past in military service.

In the lean days of old, the US military would collect cases expended during training and ship them back to Frankford Arsenal to be reloaded as dedicated training ammo.

In the black powder era, the low chamber pressures and the blackpowder fouling almost completely masked the effects of mercury on the cases.

When the US switched to smokeless powder, two things happened -- chamber pressures rose dramatically, which drove the mercury into the brass much more deeply, and powder fouling was eliminated, heightening the first. Brass weakening isn't visible to the naked eye - it only shows up when the case fails, usually by it breaking in two around the spot of greatest weakness.

Shortly after the Krag rifle was adopted, reloaded ammo used in training begain to show a high number of case failures. This was traced back to the mercury, and the military initiated a crash course to develop a new primer.

The new, mercury free primers were pretty much totally rolled out by 1900.

Corrosive priming, on the other hand, was used straight through WW II and into the early 1950s before it was eliminated in the US supply cycle. The exception was M1 carbine ammo, which was never primed with corrosive primers.

There have been a FEW exceptions to this rule, in that some match ammo was loaded, at various times, with mercuric and corrosive primers. Many match shooters still feel that the old priming compounds give better accuracy results. These cases came in boxes (most manufactured at Lake City) that distinctly identified the cases in question with a statement that they were not to be reloaded.

The corrosion you're seeing on the exterior of your cases is a sign of improper storage and thus exposure to water or other contaminants.

JNewell · June 29, 2006, 07:09 PM

Thanks, Mike. I had assumed it had developed from the inside out.

Out of curiosity, I've read about the priming of M1 Carbine ammunition before. Was there a reason for use of non-corrosive priming in that ammo? (Is it as simple as the fact that it was a fresh start?)

**Mike Irwin** · June 30, 2006, 01:09 AM

The design of the gas piston on the carbine was the driving consideration. It couldn't be disassembled (short of in an armorer's hands) so it would have been very problematic to remove all of the corrosive salts.

By going with non-corrosive priming, that wasn't a consideration.

Back to the brass...

Any corrosion originating from inside the case is most likely the result of powder that is starting to decay.

dogfood · July 2, 2006, 01:08 PM

Quote:

Think that primers are ever less likely to deteriorate. Certainly hope so as I have 275,000 in the garage.

Ken, I hope by "garage", you mean that "building FAR AWAY from the house".

I am currently shooting Winchester primers that I bought in 1989 and Winchester powder that I bought in 1991. Typically, its been stored in the basement, but I have moved twice since then, so it has spent limited time in a hot truck. Zero problems so far.

dogfood

June 28, 2006, 12:36 AM	#27
Smokey Joe Senior Member Join Date: July 14, 2001 Location: State of Confusion Posts: 2,106	OK Mike! Mike Irwin--I stand corrected. Did a little more checking after seeing yr post. I was wrong, it IS the Potassium Chlorate, not the mercury, that brings about the rusting, just as you said. And the mercury attacks the brass. You are right, I acknowledge. __________________ God Bless America --Smokey Joe

June 29, 2006, 12:01 AM	#29
Mike Irwin Staff Join Date: April 13, 2000 Location: Northern Virginia Posts: 41,390	"Does that account for the occasional weakened or through-and-through corrosion I've found in CMP LC .30-06???" No. By the time the .30-06 entered service, mercuric primed ammunition was pretty much a thing of the past in military service. In the lean days of old, the US military would collect cases expended during training and ship them back to Frankford Arsenal to be reloaded as dedicated training ammo. In the black powder era, the low chamber pressures and the blackpowder fouling almost completely masked the effects of mercury on the cases. When the US switched to smokeless powder, two things happened -- chamber pressures rose dramatically, which drove the mercury into the brass much more deeply, and powder fouling was eliminated, heightening the first. Brass weakening isn't visible to the naked eye - it only shows up when the case fails, usually by it breaking in two around the spot of greatest weakness. Shortly after the Krag rifle was adopted, reloaded ammo used in training begain to show a high number of case failures. This was traced back to the mercury, and the military initiated a crash course to develop a new primer. The new, mercury free primers were pretty much totally rolled out by 1900. Corrosive priming, on the other hand, was used straight through WW II and into the early 1950s before it was eliminated in the US supply cycle. The exception was M1 carbine ammo, which was never primed with corrosive primers. There have been a FEW exceptions to this rule, in that some match ammo was loaded, at various times, with mercuric and corrosive primers. Many match shooters still feel that the old priming compounds give better accuracy results. These cases came in boxes (most manufactured at Lake City) that distinctly identified the cases in question with a statement that they were not to be reloaded. The corrosion you're seeing on the exterior of your cases is a sign of improper storage and thus exposure to water or other contaminants. __________________ "The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower.

June 30, 2006, 01:09 AM	#31
Mike Irwin Staff Join Date: April 13, 2000 Location: Northern Virginia Posts: 41,390	The design of the gas piston on the carbine was the driving consideration. It couldn't be disassembled (short of in an armorer's hands) so it would have been very problematic to remove all of the corrosive salts. By going with non-corrosive priming, that wasn't a consideration. Back to the brass... Any corrosion originating from inside the case is most likely the result of powder that is starting to decay. __________________ "The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza Baby Jesus cries when the fat redneck doesn't have military-grade firepower.

June 27, 2006, 11:10 PM	#26
Art Eatman Staff in Memoriam Join Date: November 13, 1998 Location: Terlingua, TX; Thomasville, GA Posts: 24,798	I inherited my father's .220 Swift and a bunch of ammo. From the benchrest, I get just inside one MOA. The ammo was loaded in 1969. It worked on prairie dogs, a couple of weeks back. I've shot some 1968 .243 stuff I'd loaded; same old 3/4 MOA, but point of impact a bit lower than new stuff. I have some steel-cased .45ACP, EC 43 headstamp, that shoots just fine. Art

June 29, 2006, 07:09 PM	#30
JNewell Senior Member Join Date: March 12, 2000 Posts: 1,092	Thanks, Mike. I had assumed it had developed from the inside out. Out of curiosity, I've read about the priming of M1 Carbine ammunition before. Was there a reason for use of non-corrosive priming in that ammo? (Is it as simple as the fact that it was a fresh start?)