#2272373 - 06/24/08 09:16 AM
Re: Hot Cases - Ouch!
[Re: himmelrr]
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Ol` Joe
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Any ideas what is causing this?
Burning gun powder. 
Brass absortbs heat very well. All cartridge cases are hot after fireing. Semi-autos eject the case though before the chamber has time to draw heat from it and they retain more heat because of this.
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#2272419 - 06/24/08 09:44 AM
Re: Hot Cases - Ouch!
[Re: Ol` Joe]
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dubePA
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Yep. Nothin' like a few hot cases down the back of the neck from your "neighbor's" AR15, while shooting rapidfire from prone.
Mmmm, mmm. ;O)
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#2272522 - 06/24/08 10:45 AM
Re: Hot Cases - Ouch!
[Re: himmelrr]
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1234567
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Cartridges fired in gas operated rifles is much hotter that that fired in other types of repeating rifles and single shots. The same is true for some auto-loading handguns.
You can test this by firing a cartridge in a bolt action and quickly ejecting the case. The case might be warm, but not too hot to hold in your hand. It would be unreasonable to expect that the bolt action cartridge would have cooled this much quicker than one fired in a gas operated rifle.
What happens is, the ejection cycle begins while there is still hot cartridge gases in the barrel and chamber area. Then the gases, when they come into contact with the outside atmosphere, expand and get very hot. The cartridge, still being in, or partially in the chamber, surrounded by gas heated by the influx of oxygen is what makes the cartridges hot.
This is normal. It does the same thing in M1s, and M14s, and machine guns. Gas operated rifles seem to be the ones with the hotter cases. The brass from recoil and delayed blow back actions is also hotter than that of brass fired in non-semi-autoloading guns, but not as hot as the brass ejected from gas operated rifles.
The reason for this is that there is a gas port midway or further out on the barrel. These gases escape through the vent hole while the bullet is still in the barrel. The hot gases vent back through the gas operated mechanism, operating the bolt, and coming in contact with the cartridge brass.
With manually operated rifles, the gas, although pretty warm, escapes through the muzzle. There is very little heat generated inside the cartridge case when the rifle is fired.
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#2272610 - 06/24/08 11:31 AM
Re: Hot Cases - Ouch!
[Re: 1234567]
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himmelrr
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Cartridges fired in gas operated rifles is much hotter that that fired in other types of repeating rifles and single shots. The same is true for some auto-loading handguns.
A Remington 760 is not a semi-auto but a pump action.
Thanks for the reply though. I guess it's not a big deal.
RH
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#2272814 - 06/24/08 01:30 PM
Re: Hot Cases - Ouch!
[Re: himmelrr]
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dubePA
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As noted, the longer the spent case remains in the chamber, the more heat that is absorbed by the steel that makes up the chamber. Usually a few seconds (usually more) might pass from the time the cartridge is fired in a bolt or lever action, until the action is cycled. You may be working the pump action a bit quicker?
I've never experienced much in the way of "too hot" cases in anything but a semi-auto centerfire rifle, but then I haven't owned a M760 in some time and may have forgotten? Only powder I ever used in my pump (30-06), was IMR 4350.
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#2272860 - 06/24/08 02:03 PM
Re: Hot Cases - Ouch!
[Re: himmelrr]
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High_Brass
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Registered: 01/09/04
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Cartridges fired in gas operated rifles is much hotter that that fired in other types of repeating rifles and single shots. The same is true for some auto-loading handguns.
A Remington 760 is not a semi-auto but a pump action. Thanks for the reply though. I guess it's not a big deal. RH
I have that very same gun and I know what you're talking about. Brass comes out branding iron hot, even on a cold day/first shot/etc. I have no idea what the deal is but apparently it's rather common. FWIW, my handloads are not stout by any means so that's not a factor. I have shot factory ammo through the gun and just as you posted, had the same thing happen. I don't think it's anything to worry about unless the spent brass goes down a shirt sleeve or something!
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#2272944 - 06/24/08 02:43 PM
Re: Hot Cases - Ouch!
[Re: High_Brass]
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1234567
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"A Remington 760 is not a semi-auto but a pump action."
My mistake. In that case, I don't have any idea what is causing the hot cases.
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#2275688 - 06/25/08 08:23 PM
Re: Hot Cases - Ouch!
[Re: 1234567]
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bja105
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Recoil starts moving he slide back, extracting the empty immediately after firing, when the case is at its hottest. It looses contact with the chamber before the barrel steel can absorb the heat.
I have noticed this on a 30-06 760, but not on a light recoiling 25-06. I think the 25-06 stays locked up until the shooter works the action. Recoil unlocks the action on the 30-06.
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#2290125 - 07/03/08 11:58 AM
Re: Hot Cases - Ouch!
[Re: bja105]
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Fast_Ed
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I have a real nice scar on my left forearm where a hot .30-06 case from one of my Garands found its way inside the open elbow zipper of my shooting coat. I couldn't get it out easily and it burned me pretty good. As some have speculated, I would agree that the length of time the case is in the chamber after firing and before it is ejected, either manually or automatically, directly impacts the temperature of the case. The case is where the initial combustion takes place. Unless the heat has some time to migrate to the rest of the surrounding steel, it will remain in the case and the case will be hot. Since the bolt is, as most have written, the slowest action type compared to autos and pumps, the case in autos and pumps, when operated at their maximum speed, will be hotter than a bolt. If a pump is operated at the same speed as a bolt, intuitively, I would expect the case temp to be about the same, except for the influence of the differences in chamber dimensions and surrounding steel.
Fast Ed
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#2290369 - 07/03/08 02:10 PM
Re: Hot Cases - Ouch!
[Re: Fast_Ed]
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Jeff_O
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Cases from my bolt guns or levers come out warm.
Cases from my AR's and M14-pattern rifles I have owned come out very hot.
I don't know why; 1234567's explanation makes sense though.
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#2290624 - 07/03/08 05:09 PM
Re: Hot Cases - Ouch!
[Re: Jeff_O]
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Fast_Ed
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1234567's explanation would be more sensible if the hot gases from an M1A or a Garand gas port actually contacted the case. They are piston operated and, as such, the gases do not contact the case from the gas port as they do on an AR.
Fast Ed
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#2291944 - 07/04/08 10:17 AM
Re: Hot Cases - Ouch!
[Re: Fast_Ed]
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PPosey
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Playing with a win 94 one day seeing just how fast I could keep 7 rounds on target I had a hoter than hot case fall down the back of my shirt on shot 5-6, burnt my neck and the small of my back, made for a nice little dance as well
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#2292179 - 07/04/08 12:29 PM
Re: Hot Cases - Ouch!
[Re: PPosey]
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1234567
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"1234567's explanation would be more sensible if the hot gases from an M1A or a Garand gas port actually contacted the case. They are piston"
I don't think that it is the hot gases contacting the case. I think it is the gases inside the barrel heating up from contact with the atmosphere as the bolt is opening to eject the case.
Think about it. Even with a bolt action, working the bolt at a normal pace, the case does not stay in the chamber long enough for the barrel to absorb the heat from a really hot case. And what happens if you shot rapid fire and the barrel became very hot? Would the case remain in the hot barrel long enough for the barrel to heat the case hot enough to make a blister?
When those escaping hot gases from the partially open bolt come into contact with the oxygen in the air, it seems to me like the gas would burn more violently and hotter.
This is all theory on my part. I just don't think the case is in the chamber long enough for the barrel to absorb a lot of the the heat, if the heat comes from the burning of the powder.
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