Temperature of .30-06 shells

[GarandOwner]

Being an engineer little things intrigue me. I was at the range today, and I brought one of my M1 Garands, and my 1903A3. After shooting the exact same ammunition out of each (150 gr A-max in front of 47 gr of IMR 4895 out of Federal brass) I noticed that when the spent brass came out of the 1903A3, the brass was cool enough that you could hold it in your hand, where as the brass from the garand was too hot to hold for about a minute. My question, is what do you think the cause of this is? Any thoughts?

The only thing I can think, is that mabye the chamber of the Garand is tighter than the 1903, causing it to have a greater pressure hence greater temperature.

 

[Grape Ape]

I would attribute it to the longer time the shell spent in the chamber transferring after firing in the 1903. The steel action would be able absorb the heat a lot faster than the air the Garand’s shells were flying through almost immediately after firing.

 

[JesseL]

Were you firing both rifles at about the same rate? If you were firing the Garand more rapidly it could be as simple as the chamber being hotter.

Another thought, perhaps the fact that the 03A3 doesn't immediately eject the fired case allows the chamber to absorb more heat from the case before you eject it? Edit: Grape Ape beat me to it.

 

[DevilDog0402]

Or maybe a "looser" chamber would allow the brass to expand/stretch more making the brass hotter?

I am not an engineer or physicist, just a thought...

 

[GarandOwner]

Both were fired at the same rate, I noticed it from the first shot out of each....well first shot out of the garand. I went through 25 rounds with the 1903A3 and each time you could hold the shell imediatly after it came out of the chamber. Both chambers were free from grease and oil. I fire 1 shot at a time from my 1903, so it is, fire, cycle, and when i open the bolt I hold me hand out and let the shell drop into it. It is almost cool to the touch, where as out of the garand, it has to cool for a miniute before it can be held. The 1903 is minty, so It shouldnt be more worn than my Garand.

 

[351 WINCHESTER]

The reason your brass is hot from your grand is due to violent friction. Same thing with any semi auto, even a .22.

 

[JesseL]

It would be interesting if your Garand had an adjustable gas port that you could turn off and see what difference you get with manually cycling the action.

 

[Nhsport]

The heat comes from the hot gasses that were inside the barrel/case as the case is fired.
In the bolt gun the brass case is in nearly perfect contact with the chamber as it has been expanded by the high preasure . The small mass of the brass case will transfer heat energy fairly quickly to the realitively high mass of the steel chamber. It seems like you are working the bolt and removeing the case fairly fast but actually it is 2 or 3 seconds or longer.
Compare this to a "gas gun" where the case is removed from contact with the chamber in a fraction of a second. Most of the heat transfer stops as soon as the case starts moveing and at that point there is still hot gas on the inside adding heat energy. Possibly the friction of the case being slid out of the chamber adds some friction energy also.
An interesting test would be one guy running the bolt gun and dumping cases out to the hand of a second guy who would compare a case run out at normal speed (3 sec+/-) with one kicked out as fast as possible (3/4 sec?).
Another test would be a sks with cases ejected by the gas system ,then turn the gas port off (grenade position) with a hand ejection as fast as possible right after grabbing the trigger

 

[dmazur]

I also have a Garand and have noticed the hot brass on ejection. I have a Ruger #1 (also .30-06) that has cool brass as you describe for the bolt action. Also have a Winchester 1895 (.30-06) that has cool brass as you describe.

A co-worker has a Remington 740 in .30-06 that has hot brass.

This much evidence seems to support the theory that the autoloaders eject the hot brass before it can transfer its heat to the chamber.

 

[jpwilly]

My Mossberg ATR 30-06 Bolt gun has WARM brass Factory or Reloads. They can be handled. My Nagants 7.62x54R brass is very freakin HOT - Reloads! Don't know why?

 

[Swampy]

Garand owner,

Grape ape and Nhsport are correct.

The heat of the fired cartridge wicks out of the brass to the chamber walls of the '03 in just a second. The M1 kicks the brass out too quickly for this to happen.

Heat caused by friction of removal from chamber??? Sorry, but NO WAY. The amount of friction it would take to cause the brass to heat up to skin fricaseeing tempurature would also preclude the bolt from removing it from the chamber. By the time the bolt begins it's rearward movement the brass is no longer under pressure from bore gasses and has relaxed from full obturation. If this were NOT so the bolt would be pulling rims off the brass.... and even if it wasn't, there would be massive rub marks left on the brass from the chamber walls. There are not....

Also, the taper of the body of the brass case of rifle ammo causes complete separation from contat with the chamber walls with only minimal movement from full battery. They are intentionally DESIGNED this way especially to preclude any form of gripping, contact..... i.e. friction, with the chamber as it's being removed.

Best to all,
Swampy

Garands forever

 

[Dave P]

The 03 brass is cooler, because all the heat energy is converted to pain when it slams your shoulder!!! Conservation of energy. They are not fun to shoot.

Now the Garand is a blast to shoot all day.

 

[Slamfire]

Unlock in a Garand/M1a mechanism is about 2.3 milliseconds. Not only does the Garand open far sooner than a human operated bolt, but the mechanism actually opens up when there is pressure in the barrel. It is called the "residual blowback effect". The pressure has to be low enough so that the cartridge does not rupture (LT 650 psi or so). This extra pressure adds a bit more of a kick to the mechanism and increases the time that there is useable energy to keep things moving.

You have noticed one of the side effects: hot brass. Another is that cases gets stretched because they are being yanked off the chamber walls while there is still pressure in the barrel.

And now you can deduce why you should not hot load these mechanisms or use powders that give too high of a port pressure.