I apologize if I have posted this question before. I could not find it in a search.

I have loaded shotgun shells, raw powder, and primers that have been in my garage for a approximately 10 years. They definitely have been kept dry, I live in the Phoenix area of Arizona. My question is with the heat. Do powder and primers break down over time in extreme temperature swings. This area can get as cool as the high 30's for a low in the winter. With highs between 110 and 115 in the summer. You add a hot pick-up engine to that garage and the temperature can soar.

Should these items be disposed of, or are they okay to use?

Thanks.

Might be OK and might not .. Likely are .. Maybe ..

If in doubt , chunk 'em ..

Smell the powder , if it smells like rotten eggs or funk in general , toss it ..

Powder is affected by heat faster than cold. Your high temps are definately high enough to speed up the decomposition of smokeless powder. There are two ways to tell if your powder is going bad. The first way, and best way, is to look at it. If it has what looks like rust powder(rust colored dust) in it then your powder is going bad. It is losing its power. If you are loading mild to midrange loads and you are ok with the reduction in power then use it until it won't work. The most dangerous thing that will happen is you might get a bullet stuck in the barrel if you load too light.
Oh! the other way to tell is by smelling it. If it begins to smell like vinegar then it may be going bad.

How do you dispose of powder that is bad? Well, the next time you are tilling your garden for fertilizer pour it into the ground. It is high nitrogen fertilizer and there is very little in it to harm your plants. I am not sure I would use it in a vegetable garden but it will work great for flowers and grass as long as you keep it watered. (the buffers do not keep it from burning your plants) If you were in my part of the USA you could just wait for a rainy day and spread it on the lawn - not sure i would want to do this in Phoenix, Arizona.