Heat and barrels

dakota1 · Posted: Wed Sep 12, 2007 6:55 am Post subject: Heat and barrels

What is the issue with a hot barrel? I have been told my whole life that you don't want your barrel to get hot, but I am not sure of the reasoning. If it is to avoid expansion, and zero change, wouldn't floating the barrel eliminate that? What am I missing?

Thanks for any input.

roklok · Posted: Thu Sep 13, 2007 12:16 am Post subject: Re: Heat and barrels

Continually shooting a firearm whose barrel is REALLY hot can shorten the life of a barrel. A hot barrel often will shoot to a different point of impact even if it is free floating due in part to internal stresses in the barrel steel that can change with temperature.

Vince · Posted: Thu Sep 13, 2007 12:25 am Post subject: Re: Heat and barrels

Heat is the main reason machine guns are fired in bursts and not continually. A few hundred rounds fired continuously is almost enough to strip the rifling out completely.

I have seen machine gun barrels that hot that you can almost see through them. I got my butt kicked big time for that one. Laughing

So I would have to say yes to all that our mate roklok has said.....it can shorten the barrel life and it will alter the point of impact.

Cheers, Vince

dakota1 · Posted: Thu Sep 13, 2007 8:51 am Post subject: Re: Heat and barrels

Okay, I understand the internal stresses and reduced barrel life. The big question is... How hot is too hot? Not to beat a dead horse, but I am hoping to use a .270 winchester (90 gr hp) to shoot Pd. My problem is that after about 5 rounds, the barrel is too hot to grab. My guess is that this is probably too hot. I am hoping that someone will tell me I'm wrong.

Thanks for the input.

DallanC · Site Admin Joined: Jan 18, 2005 Posts: 3572 Location: Utah

What happens when a barrel gets too hot is the riflings near the throat of the chamber erode away which affects accuracy. I have a .22-250 that is eroded out so badly from abuse in my youth that my bullets are seated less than 1/16th in the case mouth in order to get out to where the lands are. Its still an extremely accurate rifle so I havent bothered to re-chamber it yet.

-DallanC

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

Heat will errode the bore, and will decrease accuracy as the bore won't shoot at the same POI the hotter it gets. Smile

Generally if I'm shooting for fun I don't really pay much attention to it. As I generally shoot slower semi-automatic fire, but if your shooting even in smaller bursts for a long time in full automatic fire the barrel will get hot, and thats why machine gunners in the military are issued more then the barrel attached to their machine gun so they may change it out to get it to cool down as they shoot through the other one. Smile

A Bren gun that has been shooting for a longer while if grabbed by the barrel will "glue" your hand to it because of the heat, and the scar will be visible for many decades! Shocked

Dimitri

GroovyJack · Member Joined: May 21, 2005 Posts: 621 Location: Bama

If it's too hot to grab , then yeah it's too hot , leave the bolt open and let 'er cool for five minits or so ..

I hadda 30/378 , when it was a wildcat , three rounds would nearly take the skin off your hand ..