Prvi ammo - cold?

[RyanM]

Brass tends to be really hot right after firing, right? Almost everyone has witnessed or done the "hot brass dance." With most of my firearms, I have to let the brass sit on the ground a couple minutes before picking it up.

But with my Swiss K-31 and Prvi Partisan 7.5mm Swiss ammo, I can pop off a shot, crack open the bolt most of the way, reach into the ejection port, and pluck the spent case right out with my fingers. Usually it's still cold to the touch. And I've tried holding onto the cases for several seconds, so it's not just the "feels cold at first" phenomenon.

Haven't shot Prvi in any other calibers, nor Swiss surplus ammo in the K-31, so I dunno if the ammo brand is what's causing it, but that seems like the safest bet to me. Does Prvi use some kind of low-temperature powders? The ammo definitely isn't weak or anything. Kicks about as hard as a .308.

 

[230RN]

You did not state whether in the first instance, where you had to let the brass lie there for a while before you could pick it up, you were using an autoloader.

Hot and cold is relative, but in general, in autoloading firearms, the brass does not have time to transfer its heat to the chamber walls before it's yanked out.

In manually-operated rifles a lot of the heat does transfer, even in that second or two before you open the action and extract the case.

I'm sure there are variations in loading which will also affect this, and it is known that double-based (nitroglycerine) powders burn hotter than single-based powders.

However, for the most part, it is the amount of time the case sits in the chamber which affects the temperature of the brass when it is extracted, as well as the thermal mass of the cartridge case. A .22 rimfire may get hot in the chamber, but it is so small and light, it will lose its heat quickly.

And I would suspect, without actually knowing, that laquer-coated steel cases would come out at a hotter temperature than brass cases of the same cartridge.

But possibly the most energetic dances are done with big, heavy 30-06 cases out of a Garand.

Oh, how well I know that.

 

[RyanM]

Action type doesn't make much of a difference that I've noticed. Even .38 SPL ammo is typically too hot to handle right after ejecting it from a revolver, even after waiting a couple seconds before ejecting.

 

[230RN]

Maybe you should contact them and ask:

Prvi Partizan
Milosa Obrenovica 2
31000 Uzice
SERBIA

Phone:+381 31565466

Fax:+381 31563436

e-mail:
[email protected]

Use simple language, no english idioms, in your inquiry.

Could be light loads, heavy cases. Weigh case, compare, measure case volume, compare.

Any other suggestions, THR folks?

 

[Spot77]

I shot some pp 308 Saturday and I can definitely say it was hot when ejected.