I have older, pre WW2 ammunition, but that was before I found out that ammunition has a shelf life and that old ammunition blows up guns.
I found the rule of thumb for safe lifetime of ammunition is 20 years for double based and 45 years for single based powders. Heat will dramatically reduce the lifetime, as you can find in this UN manual.
United Nations (UN) Manual
IATG 07.20 Surveillance and in-service proof
http://www.un.org/disarmament/conva...20-Surveillance_and_In-Service Proof(V.1).pdf
Paragraph 7.3, how temperature reduces the lifetime of ammunition.
Old ammunition will blow up guns through a number of ways. One is with the breakdown of the powder. Reports from blowups using WW2 US ammunition indicate that the powder had broken down to a dust. With an increased surface area it is reasonable to assume the pressure curve spiked. Another is combustion instability. As the powder ages the powder grains deteriorate. A smooth pressure curve is desired during combustion. If the pressure curve is irregular, because the grains are burning unevenly, interactions between out of phase pressure waves can cause pressures to spike. Another is the migration of nitroglycerine to the surface of double based powders. When the surface is rich with nitroglycerine the initial pressure wave will spike.
Section from the Propellant Management Guide:
Stabilizers are chemical ingredients added to propellant at time of manufacture to
decrease the rate of propellant degradation and reduce the probability of auto ignition during its expected useful life.
As nitrocellulose-based propellants decompose, they release nitrogen oxides. If the nitrogen oxides are left free to react in the propellant, they can react with the nitrate ester, causing further decomposition and additional release of nitrogen oxides. The reaction between the nitrate ester and the nitrogen oxides is exothermic (i.e., the reaction produces heat). Heat increases the rate of propellant decomposition. More importantly, the exothermic nature of the reaction creates a problem if sufficient heat is generated to initiate combustion. Chemical additives, referred to as stabilizers, are added to propellant formulations to react with free nitrogen oxides to prevent their attack on the nitrate esters in the propellant. The stabilizers are scavengers that act rather like sponges, and once they become “saturated” they are no longer able to remove nitrogen oxides from the propellant. Self-heating of the propellant can occur unabated at the “saturation” point without the ameliorating effect of the stabilizer. Once begun, the self-heating may become sufficient to cause auto ignition.
As NOx is released within the case it attacks the brass. Nitric acid gas is a by product of NOx. I had the case necks crack on 700 LC Match cases loaded with surplus powders. As the stabilizer is depleted in old powder more and more NOx gets released inside of the case. I have heard of corrosion between bullets and case necks causing blowups, that corrosion is probably due to NOx.
I am pondering about the best thing to do with my old surplus ammunition. I think one approach is to pull the bullets, dump the powder, and see if the cases have internal corrosion. Cases that are in good shape I may reload with fresh powder.
This powder is from a FA 11-1898 30-40 Krag cartridge. Obviously it is bad.