Shell casing temps

Cerebus

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I noticed something odd (to me anyway) the last couple weekends at the range. The shell casings coming from my AR10 are very hot, too hot to pick up right when they're ejected. This seems normal to me. But shooting the very same FGMM out of my R700, I can catch the casing in my bare hand as I pull the bolt back and it is hardly even warm. The only thing I can think of is the AR10's gas system, but I wouldn't think it would add that much heat ...or is there some other reason?
 

DeeGee

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Jan 25, 2009
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Re: Shell casing temps

I've noticed the same - I always catch cases as they are ejected from my Rem 700 and they are barely warm, while my brother in the next lane is pelting me with hot brass from his M14.
 

95LTZ

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Re: Shell casing temps

Not exactly sure but my guess would be since brass is a good conductor is doesn't have enough time to pass the heat to the chamber area. Since the bolt normally isn't functioning that fast the brass has more time to pass it's heat to the chamber. I remember decades ago an old guy at the time told me "Son, the nice thing about a bolt gun is you don't have to wait on the automatic just go ahead and shoot as fast as you can, now shoot me another possible"
 

Cerebus

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Re: Shell casing temps

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 95LTZ</div><div class="ubbcode-body">Not exactly sure but my guess would be since brass is a good conductor is doesn't have enough time to pass the heat to the chamber area. Since the bolt normally isn't functioning that fast the brass has more time to pass it's heat to the chamber. </div></div>

This completely makes sense to me.
 

Sig685

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Re: Shell casing temps

95LTZ is exactly correct; the shell casing of an full/semi auto does not have the time to pass its heat to the chamber wall and so it is ejected with a large majority of the heat it just generated. This was one of the problems with caseless ammo, there was no vessel to take away some of the heat generated by the firing.
 

trilogymac

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Re: Shell casing temps

What I have noticed, is that the case temp varies with different powders. Possibly due to burn rate?

Hope this helps,

Trilogymac