HEAT

[x_wrench]

growing up, my dad always taught us that when the barrel feels hot, quit shooting until it feels cool again. that is not a very scientific way of doing things. but not many of us want to take some sort of thermometer into the feild or range with us. i am just wondering how hot is to hot on a standard production barrel. like say a remington 700 or a marlin lever gun in a rifle caliber. by how hot, i am thinking of how hot before the barrel is damaged, not necessarily when the accuracy falls off, or the p.o.i. changes. i have no idea if a barrel would take a set at a certain temperature, maybe ruin its accuracy?????? i just know i never want to get a barrel that hot.

 

[Vern Humphrey]

If it starts to glow, it's definitely too hot.

In Viet Nam, I saw the barrels of M60s and M2s glow -- in fact, I've seen M2 barrels get so hot they start to droop, and the bullet, continuing on in a straight line, doesn't make the curve in the heat-softened steel and comes out the side.

 

[Sky]

Like Vern I have seen hand guards (wood) and barrels a glowing and a smoking....But most times the weapons are owned by some government and can be replaced by going to an armor and there was some need for that rate of fire. I have seen people do a 5 mag bump fire just because they could. Your dad might have been a bit conservative but again he was trying to save the cost of a new rifle, "just in case". Myself if I can not hold the barrel with a bare hand then I open the bolt and try to let it cool off a bit before shooting. We have guys who shoot hundreds of rounds on a weekend and do not seem to have a problem so maybe my dad and yours were cheap charlies? Hahahaha Dad was a machine gunner with Patton in WWll and he could have been saying that so I wouldn't burn myself?.

 

[lencac]

I usually put it down when I can boil spit on the barrel

 

[-v-]

As long as you're firing 200 rounds or less in a minute's span, the barrel will probably be OK. I believe 200 rounds a minute is about the maximal sustainable firing rate of a SAW, not to be confused with its cyclic rate which is closer to the 1000 rounds a minute rate.

 

[DC3-CVN-72]

WOW!! Vern, I can honestly say I have never herd of an M2 BBL. doing that. I guess you must have to have been there & done that. Also, I'd like the time to thank you for your service.

 

[okiewita40]

If the head space and timing on an M2 are not set right it can happen. I seen happen once. There was a contest once in one of the units i was in. We had to assemble, set head space and timing. Then mount and fire 200 rounds. The winners linked together all 200 rounds and fired it in one long burst. I wathed the barrel turn red then white. When the firing stopped. you could see the barrel drooping.

 

[MrCleanOK]

by how hot, i am thinking of how hot before the barrel is damaged

Fear not. You probably couldn't do it to a bolt gun if you tried. With the money you would spend in extra detachable box magazines and ammo so you could reload fast enough to try, you could just buy a second rifle. Accuracy concerns from a heating barrel? Yes, completely valid. But you're simply not going to permanently damage a barrel unless you're purposely trying, and even then you probably wouldn't be able to do it.

 

[kwelz]

Well I have literally melted the handgun off of an AR. (POS Oly that didn't have shielded handguards)


I have also had my suppressor so hot I swear it had a faint glow to it.

Nothing wrong with shooting a gun hot. Now of courser there are extremes. I think most of us have seen the videos of the M4s ran to destruction. It took hundreds of rounds in a couple of minutes but the barrel ruptured on one and the gas tube melted on another.

 

[Jon_Snow]

Two things happen when a barrel gets hot. One is it could distort or weaken enough that it's not longer safe. As mentioned above, that's pretty darn unlikely unless you're tyring to do it or you're using a fully automatic weapon in a warzone. The second thing happens at a much lower temperature, and that is that as the barrel heats up it softens slightly. This won't make it unsafe, but it will wear faster. How much faster is dependent on several things like how hot exactly, what caliber you're shooting, etc. Also, unless you're a competitive shooter, most of us will never wear out a barrel, so shortening it's lifespan slightly won't make any impact to you.

Long story short; nothing bad'll happen immediately if you let your barrel get hotter, and it probably won't have any significant long-term effects either.

 

[W.E.G.]

i am just wondering how hot is to hot on a standard production barrel. like say a remington 700 or a marlin lever gun

I guarantee you cannot possibly get it that hot.

 

[x_wrench]

all of this is good news for me. i have been taking 3 guns to the range, geting everything out for all three, and shooting (depending on the weather) between 2 and 5 rounds. set that gun aside, shoot another, repeat. in hot weather in the sun, there are times that i have had to wait ten minutes while not shooting, trying to concoct some sort of shade to help them cool. the thought of drenching them with water had crossed my mind. but that would be a lot of water to drag along.

 

[Art Eatman]

I very rarely do a bunch of bangity-bang with a semi-auto. With my bolt actions, I generally stop for a cool-down when the barrel becomes uncomfortably hot to the touch. In a sort of FWIW belief, I think that the leade might burn more than at some sort of "normal" rate.

I did occupation duty in Korea, '54/'55. Ack-ack outfit; an M16 halftrack with a quad-50 turret in back. The ammo came in 105-round belts; two belts to a can. Yup, at the range, barrels will droop.

 

[Ky Larry]

I have an old Ruger-77V two tone in .223 I bought from Bud's in 1987. It has had thousands of rounds thru it and it still shoots bug holes. It's never had more than 5 shots thru it without a cool down.

 

[MachIVshooter]

Depends on the gun, the cartridge and the gun's purpose.

Handguns? Good luck ever getting one hot enough to do any damage at all.

Rimfires? See above.

AR's, AK's and other autoloaders? Unless they're precision rifles, I wouldn't worry about it. You're not gonna get rounds off fast enough to scorch them unless you have a huge supply of mags and a very fast finger.

Bolt rifles? This is where there are different schools of thought. Any of the ones I have scoped and expect to maintain good accuracy, I never let them get too hot to firmly grab the barrel. This is especially important with cartridges that are pushing overbore, like the .220 Swift, the RUM's, etc. When the barrel heats up, throat erosion is accelerated. I've found on busy dog towns, my .220 needs to cool after 10 or 12 rounds in rapid succession. It is a consistently sub-MOA (.77 MOA average) rifle, and I want to keep it that way as long as possible.

 

[Powderman]

Fear not. You probably couldn't do it to a bolt gun if you tried.

Oh, yes you can. Very quickly, as a matter of fact.

Here is a description of what happens inside your rifle at the moment of firing:

We know that smokeless propellant burns--it does not explode. At ignition, the powder burns--which creates gas, which increases pressure, which increases the burn rate, etc.

Pressure builds inside the pressure vessel (the loaded round) and then makes the weakest part of the vessel fail--in this case, that is the seated bullet. It breaks its friction lock on the case neck and starts to move down the barrel.

Incredibly hot gas is pushing the bullet, and is STILL expanding violently. The leade (first part of the rifling that accepts the bullet) gets heat at a level found in metal-cutting torches focused on it--under tens of thousands of pounds of pressure. This heat, if allowed to continue, would turn barrel steel into liquid VERY fast. However, the speed of the bullet down the bore allows the vessel's area to increase quickly; thus, the pressure is decreased slightly until it all vents from the muzzle upon the exit of the projectile.

This heat dissipates rather quickly.

Firing ANY rifle quickly will cause the metal to retain that heat, until the point of plastic (temporary) deformation is past. Now, the heat and pressure actually moves and displaces metal. In addition, particles of propellant residue blast the surface of the barrel. When the metal is hot enough, it actually dulls the lands and surface area of the barrel grooves. (This causes bores to achieve a "frosted" appearance that is not easily removed--if ever.)

Something else to think about--the residue of the burning propellant is primarily hard particles of carbon. Carbon, under heat and pressure, turns into diamonds.

Chrome lines barrels were spec'd by the military because the chrome is tough, and resists permanent deformation longer than unprotected barrel steel. Yet, it still gets damaged if abused.

I shoot all my long guns in strings no longer than 10 rounds. After each string, I let the barrel cool for at least 15 minutes. After 40 rounds, the rifle gets cleaned with Hoppe's and is allowed to cool for a full half-hour.

I have personally seen rifles with damage to the leade after a single range session, due to rapid firing, and not allowing the barrel to cool.