AR barrel heat, how much is too much?

[TonyAngel]

I think you're worrying about nothing. Shoot the rifle as you need to. I don't do mag dumps, but I've run drills and stages that have left my rifle so hot that I have to wear a glove to be able to hold it. Touching the barrel with a bare hand would instantly burn you. I've seen no negative effects from just using my AR. Besides, AR barrels are cheap and easy to replace.

 

[briansmithwins]

After 490 rounds on full auto M16 barrels rupture, which was probably too much. Somewhat surprisingly, M4 barrels go for longer: https://apps.dtic.mil/dtic/tr/fulltext/u2/a317929.pdf

BSW

 

[sarduy]

Your finger will get tired before you can overheat the barrel to the point it can cause serious damage.

if you think your barrel heated up with mag dump, wait until you put a suppressor

 

[Sniper66]

Too much heat?? Lots of good comments about AR and that kind of rapid shooting so I'll not comment on that. With accuracy being my primary goal (I don't shoot in competitions.), I've had rifles that were adversely affected by heat. Had a Ruger 77/17 with a slim sport barrel that would get too warm with repeated shots and 50 yd groups would grow from a 1" group to a 3" string. Before figuring that out I missed some easy prairie dogs shots. I got rid of the rifle.

 

[243winxb]

https://apps.dtic.mil/sti/citations/AD0822736

DEVELOPMENT OF A STELLITE-LINED, CHROMIUM-PLATED BARREL FOR 5.56MM MACHINE GUN

The procedure as developed by Springfield Armory for design and fabrication of a stellite-lined, chromium-plated barrel for the 5.56mm machine gun is described. Results of erosion tests of the stellite-lined barrels, standard barrels, and two other types of barrels show that the stellite-lined barrels are superior in erosion resistance. One of the stellite-lined barrels was fired 43,994 rounds prior to rejection. A maximum of 12,476 rounds was fired from one of the standard barrels prior to rejection. The two other types of barrels - a standard barrel with a nitrided bore and a barrel of two-piece construction - were fired 29,874 and 990 rounds, respectively, before rejection. The two-piece barrel has an 18-inch forward section made from Cr-Mo-V steel and the rear section, including the chamber, is made entirely from stellite. All barrels were rejected on the basis of the projectile instability criterion - 15 degrees yaw of 20 per cent of the projectiles fired. All barrels were fired at an average rate of 200 shots per minute.

An AR15 barrel would outlive many owners at these rates.

Overall, just buy a new cheap barrel if the old one fails.

 

[David Hoback]

It was mentioned your finger will get tired first. Correct. You have semi, not full auto. You simply cannot shoot fast enough for the amount of time necessary to permanently damage the barrel from heat. That said, every barrel has a specific round count to which it will degrade accuracy to the point of not being serviceable. Doesn’t mean you can’t still fire it safely. Of course it will still fire just fine. But it’s accuracy will be terrible.

Another thing which makes this all a mute point.,, even if you have a full auto.... and as many mags as you need pre-loaded... the gas tube will rupture LONG before the barrel is compromised. This was part of Eugene Stoner’s brilliant design thinking.

I’m surprised no one else has made mention of this.

 

[CapnMac]

Pretty much, unless the barrel changes color or furniture starts to deform or melt, you are no where near the edges of the envelope.

Bang out 5 rounds of 8m Mauser through a Kar98K as fast as you can, and grab the handguard in front of the rear sight, it will be hot to the touch.

 

[George P]

“Hot” will deteriorate a rifle barrel faster than not hot - I think that statement is general consensus. Some consider a barrel a wear item - if it wears out for whatever reason, you replace it. If a barrel is used for (say) hunting deer, shot a couple times a year to verify zero and stagnant the other 50 weeks, it should last forever (which for a human is a lifetime).
I am never a barrel heater - I shoot to relax and for accuracy - I am never in a hurry. I see rapid fire and barrel burning as a testosterone thing just before the cold beer, the “F” word, and complaining about “the old lady”.
Heating/ using up lots of ammo and barrel life appears counterintuitive to marksmanship and accuracy to me but, to each his own (as long as I do not have to be around that behavior, I do not care).

I agree.......I was at my local club (where we get individual outdoor private lanes) slowly shooting revolvers off a rest and over a chrono working on some loads when I hear someone next to me in the next space doing mag dump after mag dump. These particular lanes are only 15 yards long. After a bit their shooting stops and a young man comes around the corner to me and asks if I know anything about ARs as they were having an issue with their brand new AR. (I don't know a thing, don't own one) I directed him to the folks in the office where you sign in. About 10 minutes later the mag dumps started again, one after another as fast as they could pull the trigger. I can only imagine how hot that barrel was and the accelerated wear they just imparted on that new gun......Oh well, to each their own.

 

[Jbird45]

I agree.......I was at my local club (where we get individual outdoor private lanes) slowly shooting revolvers off a rest and over a chrono working on some loads when I hear someone next to me in the next space doing mag dump after mag dump. These particular lanes are only 15 yards long. After a bit their shooting stops and a young man comes around the corner to me and asks if I know anything about ARs as they were having an issue with their brand new AR. (I don't know a thing, don't own one) I directed him to the folks in the office where you sign in. About 10 minutes later the mag dumps started again, one after another as fast as they could pull the trigger. I can only imagine how hot that barrel was and the accelerated wear they just imparted on that new gun......Oh well, to each their own.

That sounds like abuse, and they probably don't know any better. I have seen many first time gun owners at the range recently with AR-15's and pistols.

I am not asking about pushing my rifle to the limit. I also didn't buy it to shoot like a 1000 yard benchrest rifle either. The first 2 times I shot it, I did so at a reasonable pace. Far from a mag dump, but not one round and 5 minutes of cooling. The second mag was slower as I had a bench and was working in dialing in the scope.

Last time I shot, I did 20 rounds. I fired 10 at a medium pace, and let the barrel completely cool before the next 10. That seemed to be a good pace between preservation and fun.

I asked my question to gather info on what others do. If people said go full Rambo I wouldn't have worried about it. If people said to slow down and shoot it more like a hunting rifle, I would rather know while I still have a low round count.

 

[David Hoback]

In case you are still unclear.... There is absolutely NO WAY you can shoot your AR even close to fast enough in its present form, to build up the heat required to cause it to fail. And even then, the gas tube would be the failure point,(As Designed to Be), long before the barrel. I am not making this up, nor is this my “opinion”. It just simply is. Research and see what you come up with.

 

[Jbird45]

In case you are still unclear.... There is absolutely NO WAY you can shoot your AR even close to fast enough in its present form, to build up the heat required to cause it to fail. And even then, the gas tube would be the failure point,(As Designed to Be), long before the barrel. I am not making this up, nor is this my “opinion”. It just simply is. Research and see what you come up with.

I have seen some meltdown videos on YouTube from Iraqveteran8888. He did an m&p and the plastic hand guard caught fire and the gas tube melted. And that was mag after mag after mag with a full auto lower. I suppose I am overthinking it.

 

[David Hoback]

Exactly. There ya go.

 

[cfullgraf]

My main prairie dog rifle has been an AR-15 with a 26" 204 Ruger barrel. The AR-15 is great for quick follow up shots and there have been times that I have gotten the barrel hotter than I would have liked.

I have begun to limit the number of rounds in a magazine to four or five placing a limit on how fast I can fire before I need to reload. It gives the barrel a chance to cool some.

The accuracy seems to be falling off at about 2000 rounds but I have not done an in depth test of the accuracy yet since my last prairie dog adventure. I know some of the folks shooting Service Rifle expect their barrels to start falling off accuracy around 3000 rounds or so.

If and when I truly decide my barrel is worn out, I do have a replacement barrel on hand.

 

[David Hoback]

My main prairie dog rifle has been an AR-15 with a 26" 204 Ruger barrel. The AR-15 is great for quick follow up shots and there have been times that I have gotten the barrel hotter than I would have liked.

I have begun to limit the number of rounds in a magazine to four or five placing a limit on how fast I can fire before I need to reload. It gives the barrel a chance to cool some.

The accuracy seems to be falling off at about 2000 rounds but I have not done an in depth test of the accuracy yet since my last prairie dog adventure. I know some of the folks shooting Service Rifle expect their barrels to start falling off accuracy around 3000 rounds or so.

If and when I truly decide my barrel is worn out, I do have a replacement barrel on hand.

Sounds like your barrel is meant for precision. A 26” 204 Ruger barrel. I don’t think it’s chrome lined or Nitride QPQ treated(unless you had that done separately). 204 is a known barrel burner. With 2000 rounds, I’d say you are doing very well indeed. I’ve seen typically 1500-1700 rounds when accuracy decay rears it’s ugly head with that little screamer. An untreated stainless barrel(Guessing it’s a stainless ultra precision barrel), won’t fair as well to heat as a treated or Chrome lined. (Chrome-Moly V only).

 

[rdnktrkr]

Does a barrel that gets hot enough to affect accuracy always return to where it was before or does the POI change?
I don't do mag dumps and usually use 20rnd mags, I do practice double taps but I don't think I've ever had one hot enough to affect accuracy.
For the people who shoot fast competitively do you use a portable fan to cool the barrel between sessions?

 

[Skylerbone]

Does a barrel that gets hot enough to affect accuracy always return to where it was before or does the POI change?

If a barrel shifts from heat it is due to residual stress. That means you have a not so great barrel. Fine for leisurely blasting but not ideal for long distance prairie dogs.

 

[David Hoback]

Heat affects POA period, to some degree. But if it gets so hot as to WARP the barrel, the barrel will not return to original. It will retain the new shape as it’s not memory steel. Regardless, the amount of heat enough to warp would be greater than any “spring” heat treatment could withstand anyway.

 

[briansmithwins]

Does a barrel that gets hot enough to affect accuracy always return to where it was before or does the POI change?
I don't do mag dumps and usually use 20rnd mags, I do practice double taps but I don't think I've ever had one hot enough to affect accuracy.
For the people who shoot fast competitively do you use a portable fan to cool the barrel between sessions?

For the matches I shoot the rifle gets cased as soon as you’re done shooting. It cools for until it’s your turn to shoot again.

The cost of a replacement barrel once accuracy isn’t acceptable any more is cheap compared to the price ammo and even gasoline to get to matches. And my events are local so I’m not paying for a hotel.

Barrels are a consumable item if you shoot enough.

BSW