TexasCHLforum.com

mgood wrote:

bizarrenormality wrote:I wouldn't worry about the gun but vibration and heat can do interesting things to ammo.

Deltaboy wrote:I have shot ammo that was in a behind the seat box that had been there for over 10 years of Ark /TX heat and cold and all the ammo went bang.
Winny 357 mag and CCI 22 ammo.

I have been told, by someone who's opinion I trust, that ammo kept in a vehicle should be used up and replaced occasionally, like maybe once a year.
The shape of the granules of powder is important to how fast or slow it burns. The vibrations of the road break them down into a finer powder. Probably not going to make it dangerous or make it not work, but it will change the ballistics somewhat. Probably won't matter at bad-breathe-distance of a self-defense situation.
I like to shoot a little of my carry ammo now and then, even though it's much more expensive than what I usually practice with, just so I know how it shoots, how it feels different from my practice ammo. So when I'm going to shoot up some of my carry ammo, I use some that's been bouncing around in my truck for a while and replace that with new ammo.