How does cold affect ammo?

[TonyB]

I keep my ammo for IDPA in the trunk of my car all week.I live in upstate NY,so it gets pretty cold..last night it was like 4 degrees.Will this somehow effect the ammo?I haven't noticed any problems(I've been doing it for a while)But I was wondering if the experts have any opinions....thanks

 

[Ala Dan]

Well, I'm not an "expert" by any stretch; but I don't think the cold will
affect ammo so long as its kept dry. Moisture tends too rake havoc on
most anything firearms related.

 

[GRIZ22]

Cold generally slows down the breakdown of any chemical compound (powder, primers) so as long as it's dry I don't think the cold, by itself, will have any negative effect. I wouldn't worry about letting it warm up before using it although velocity will be down a bit because of the cold and the denser air. Some reloading manuals recommend magnum primers if the ammo is to be used in extreme cold. CCI says that their milspec primers should be considered magnum for reloading purposes. I've never had any problems with factory ammo or reloads with standard primers in the cold.

 

[Curly]

Some powders are affected by cold more than others. Typically, the effect is to reduce the energy, so your ammo will shoot lower on cold days than normal temperatures. I know 452 AA powder is temperature sensitive, as is H380. For stick powders I can't speak from personal experience.

 

[cpaspr]

However -

There is the potential for condensation that sometimes accompanies metal left in a trunk. I think it somehow depends on how well the trunk is sealed though, as I've had some cars that would develop puddles inside the metal toolbox left in the trunk and major lakes in the spare wheel well, and others where nothing happened.

Personally, I don't ever leave guns or ammo in the vehicle if I can possibly avoid it.

 

[ForeverArmed]

Ditto on the condensation. Also, a lot of "thermal cycling" -- e.g., alternately cold nights and hot days over a long time -- is a great thing to avoid.

 

[billp]

22-250 disaster story

I loaded .22-250 ammo for rem 788 near max in the winter using 4895.

I shot some in the summer.

Broke off bolt trying to extact cartridge.

I returned remington 788 repair.

I sent a long letter embarrasing letter of explanation.

Remington repaired for free.

I no longer try to max velocity.

Search for "look for createrer primer"

http://mywebpages.comcast.net/bpayne37/don2/don2.htm