Was loading 50 rounds of .243 with a new can of IMR 4350. I loaded 50 rounds with maybe 15 grains remaining in the can. I had a very old can of the same to load a batch for my son's .243. We both use the exact charge, but when I threw the first pan it was way light. I hadn't touched the 10-10 scale or the thrower, so I tried again and another way light pan. The powder is around 20 years old kept in a air conditioned house and sealed tightly, it smelled like new and looked exactly like the new powder. What gives? Can powder loose weight over time?
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