I have a range of smokeless powders that are over 10 years old.
IMR- 4350, IMR-4831, Bullseye, etc.
All powders have been stored in a fireproof safe in my workshop. I loaded some of it last year, it seemed to produce consistent groups in my .7 mm Mag. and .222 mag. Anyone have any facts?
Below is what IMR says:
HOW TO CHECK SMOKELESS POWDER FOR DETERIORATION
Although modern smokeless powders are basically free from deterioration under proper storage conditions, safe practices require a recognition of the signs of deterioration and its possible effects.
Powder deterioration can be checked by opening the cap on the container and smelling the contents. Powder undergoing deterioration has an irritating acidic odor. (Don't confuse this with common solvent odors such as alcohol, ether and acetone.)
Check to make certain that powder is not exposed to extreme heat as this may cause deterioration. Such exposure produces an acidity which accelerates further reaction and has been known, because of the heat generated by the reaction, to cause spontaneous combustion. Never salvage powder from old cartridges and do not attempt to blend salvaged powder with new powder. Don't accumulate old powder stocks.