Random question i've never heard a good answer to

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mattamus1987

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I fire a .223 our of my AR. The spent case is scalding hot.

I fire a .30-06 out my browning. The spent case is barely warm to the touch.

Whats with the huge difference in temperature of the fired cases. Yes there is substantially more brass in the 30-06 case and would take more energy to heat up but is that all thats going on here? And you cant say powder burn rates because ive had .223 loads and 30-06 loads with IMR 4895 and it didn't make a difference.

Anyways this dosent really matter im just bored today.
 
Heat transfer is heat transfer - the reverse of what we experience with brass happens in cooking - after removal the tin foil covering the casserole dish will be cool to the touch in seconds - that baking dish will stay screaming hot for a looong time.
 
Is the first shot out of your AR hot? Or are you talking about one of the casings that come out after perhaps 10 or 20 or 30 shots?

The more you shoot the hotter it gets. In general an AR is going to see a much higher volume of fire than a .30-06.

I don't recall checking the first piece of brass out of my AR's so I don't know...the later ones are hotter than three hells because the gun has heated up.

Now you have me curious though...but I can't step out back and start shooting because the city frowns upon it. Now I'm stuck with a question I can't answer...thanks.
 
Heat transfer from the case to the chamber. Your .223 case is being extracted from the chamber before it can transfer much heat to the chamber walls. Fire your .30-06 out of a M1 Garand instead of your Browning, and you will have one hot .30-06 case as well.

Don
 
Surface area. The 06 has more surface area in contact with the barrel, allowing the chamber to be a better heat sink.
 
Heres a possible answer.

The .223 case is ejected instantly from your AR-15 before there is much chance of heat transfer to the colder barrel cooling it off.

Is your 30-06 a bolt-action?
If so, I don't care how fast you are operating it, you ain't as fast as a gas operated semi-auto.

So the 30-06 case has more time to cool off in the chamber before it is ejected.


rc
 
The other day I noticed something weird, ants would swarm all over our hot brass. As soon as it. Cooled down they left.

Sent from my CZ85 Combat
 
Combustion temperature of the powder used. .223 loads use a faster/hotter burning powder than 30-06. My 9mm brass is warmer than my .44 Magnum brass immediately after firing; 9mm powder, upper loads of W231, .44 Magnum, lower mid-range loads of 2400...
 
Heres a possible answer.

The .223 case is ejected instantly from your AR-15 before there is much chance of heat transfer to the colder barrel cooling it off.

Is your 30-06 a bolt-action?
If so, I don't care how fast you are operating it, you ain't as fast as a gas operated semi-auto.

So the 30-06 case has more time to cool off in the chamber before it is ejected.


rc
This ^^^
 
Combustion temperature of the powder used. .223 loads use a faster/hotter burning powder than 30-06. My 9mm brass is warmer than my .44 Magnum brass immediately after firing; 9mm powder, upper loads of W231, .44 Magnum, lower mid-range loads of 2400...
original post; mattamus1987 said:
And you cant say powder burn rates because ive had .223 loads and 30-06 loads with IMR 4895 and it didn't make a difference.
Sorry, no cigar for you, mdi.

There might be some temperature difference because the case volume is substantially smaller in the .223, contributing to higher pressure and temperature, but I am sure the difference is very small. The pressure operating range of any given powder would be the same.

Mystery. Needs more information. Action type, specific load data (so we can estimate pressure), gspn's question in post #5, etc.

Lost Sheep
 
I've wondered the same thing for a long time. I can run 5 stout cartridges through my 7 mag and the brass is barely even warm to the touch. And unless I've heated the barrel up enough to cause thermal transfer to the chamber, and then leave a cartridge in the chamber for several minutes, the cartridge doesn't get hot. But brass from the AR will come out extremely hot, even the first round.

GS
 
Like I said in post #5.

The case is being ejected from a semi-auto almost while the fire is still lit, and there is no time for heat transfer from the case to the chamber.

You can't operate a bolt-action that fast, so heat transfer is more complete, no matter how fast you try to operate it.

rc
 
mattamus1987,

does your 223 ammo have a coating on it? if so, that could be insulating and preventing the heat transfer that is happening with that 30-06 round.

murf
 
I'll buy in with RC. The same .30-06 ammunition coming out of my 1903 and my garand are two different animals as far as temperature. I'm no thermodynamics whiz, but I'm sure heat will transfer much more rapidly through metal to metal contact than through metal to air. Think double pane windows for example. Add to that the friction of being yanked from the chamber it any exists.
 
Like I said in post #5.

The case is being ejected from a semi-auto almost while the fire is still lit, and there is no time for heat transfer from the case to the chamber.

You can't operate a bolt-action that fast, so heat transfer is more complete, no matter how fast you try to operate it.

rc
Assuming your assumption is correct (bolt gun in 06 vs auto in 223) then this is the best answer. I said greater surface area on the assumption the OP was comparing apples to apples and was shooting a BAR. Even a 1/2 second delay before working the bolt allows for a lot of heat to bleed off.

Do we know for certain what kind of gun the 'Browning' is?
 
I'd guess it's because there's more mass in the .30-06 case. .30-06: ~186 gr./case, .223 ~97 gr. That's almost twice as much metal.
 
The 30-06 brass from an M1 Garand is scalding hot, just like the brass from the AR. No time for the chamber walls to cool the case in the semi-automatic.
 
223 is smaller than the 30/06 , so it heats faster , it should cool faster too take a 223 ,hold the base and then use a bic-lighter at the neck and see how fast the base gets hot , then do the same with the 30/06, and see how slow it heats up ,
this will be the same for any brass , less brass ,the faster it will heat up
or try this take 223 brass hold over open flame for 3sec, then 30/06 over same flame for 3sec, see witch gets hotter,

NOTE: I'm just guessing , and we still don't know if the OP's Browning is a BAR or an A-Bolt
 
The brass that ejects from my Win Mod. 100 auto is hotter then the gal I had out last night.

Smokeyloads
and that my friend is why we don't drink when we go shooting and do when ....... well you get the point... lol.....
 
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