Can powder go bad?

[KAB]

Can powder deteriorate over time? About two and a half years ago I load some .280 Rem. 160 gr. Accubonds with H4831. I loaded to achieve 2900 fps which the book said was max. Last month I bought a Chrony beta. The Chrony says that my rounds were traveling a lot less than 2900. I carefully load up, without pressure signs, to 2900. I then pulled the bullets from the rounds originally loaded two years ago and added powder. Same bullet, same powder (in fact it is from the same can), same case, the only difference in the two loads is the primers (original rounds are Fed. 110, newest CCI Long Rifle). The pulled and reloaded rounds are 200-250 fps slower.

Day time temperature was about 15 degrees cooler today on the pulled and reloaded than when I fired the others a month ago.

What's going on?

 

[J E Custom]

Bad powder

KAB

Yes the powder can go bad ,but if stored properly it shood last
many years. ( I still have and use some H4831 world war 2 surplus
20mm powder).

Also I shoot lot,s of 3006 GI ball thats at least 50 years old.

loading books hardly ever match the chronograph's velocities
so don't go by the books except for starting loads.

And if you change primers you should allways back off on the
powder 1 or 2 grains no mater what kind (mag or standard ).

Barrel length can effect the velocity if different from the test
barrel used in the book.

Go back to your original powder/primer/bullet load (No substitutes)
and dont wory about what the book says ,Just watch for pressure
signs and good standard devations.

I Hope This Helps
J E CUSTOM

 

[KAB]

Can Powder go Bad

Thanks I'll take all of those into consideration.