Barrel too hot?

AR/M4 AR General Discussion
1

My first AR will be finished in about two weeks. I’ve only owned bolt guns and pistols. I Shoot on a bench. With bolt guns, you don’t wan’t the barrel getting hot. After 5-10 (depending on contour of barrel) you let it cool. Could actually ruin the barrel if shooting it too hot.

But with AR’s, people at the range run through a 100 rounds in 15 minutes…Does the heat not mess up the barrel? Does it affect accuracy?

When I first take my AR to the range, I’m going to be hesistant on shooting 30 rounds without letting the thing cool.

2

Unless your doing full auto mags dumps one after the other, then you’ll probably be ok.:wink:

3

You are also babying the barrels of your bolt action rifles (not necessarily a bad thing). I got a bolt action 6mm from my father back in 1973 and I shot it plenty in the desert without worrying about overheating the sporter weight barrel and today, it still shoots just as accurate. Modern quality barrels are pretty tough and will take quite a bit of punishment regardless of action type

4

I’ve known many people who have scorched the inside of their barrels from overheating and rendered them useless.

When trying to put 5 rounds through one hole @ 200 yards, everything is taken into consideration.

5

Yes, benchrest (which different from shooting from a bench) is demanding and intolerant of barrel imperfections. Benchrest is a completely different game than shooting AR carbines for training. I have put several hundred rounds through the stainless steel my carbine in an afternoon more than a few times and see no practical difference in the accuracy. If I were benchresting my carbine and it were capable of benchrest accuracy to begin with, it might be a different story.

Don’t over think it and go shoot your AR

6

Yeah I plan on not babying it, haha thanks.

7

I don’t know anyone who has ruined a barrel in one shooting session. Maybe some machine gunners have.

8

If running an AR hot was a “bad thing” there’d be a lot more rest breaks during carbine classes.

The only provisio would be… if you can light a cigar with your muzzle device you might want to slow down a bit :slight_smile:

9

I would like some experienced individual’s input on how the barrel heating up effects accuracy.

Given, say, a Colt 6920, and shooting for 4 MOA or better from a field position, would running 120 rounds downrange in half an hour measurably degrade accuracy as the barrel heats up?

In my (limited) experience, I believe that is what happened. (not totally sure on the rounds/unit time, but what I listed above should be in the ballpark)

At an Appleseed I went through several consecutive AQTs (40 rounds each) and my groups were opening up/scores going down. I let the rifle rest for one AQT while I shot my 10/22 instead, and when I went back to the AR my groups were tighter and my score jumped back up to where it started

10

Your chrome line barrel will handle heavy firing much better than your wallet in all likelihood.

You can shoot3 or 4 mags, 100 rounds no problem, no worry.

11

If you mag dump 300 rounds on full auto, this will happen:
http://youtu.be/ISOh_s08pIE
But in semi auto, you’ll be totally fine.

12

You move to Louisiana and get a retarded show on the Discovery Chanel??? :confused:

13

Hah! You’re funny.

Nah, the OP is worried about barrel temp, so I was giving him a frame of reference.

14

That’s your normal for a bench gun. Reconcile yourself to a “new normal” in regard to your AR.

You’re comparing spun-glass to anvils. Different pattern of firearm, made to different specs, meant to tolerate different circumstances, different discipline.

With a duty-grade AR, I’m not the only one that doesn’t start thinking of anything as a “heavy” shooting day until I reach 900 rounds or so, given that I’ve participated in days of 2500 rounds/gun in a 4hr period (calm down, that was for testing purposes…not my guns :wink: ). Yes, accuracy can and will suffer when the gun gets hot/stays hot, but shooting 150 rounds as fast as you can pull the trigger is not, in and of itself, abusive. 30 rounds…? Were I to choose a word, that word would be “Pfft…”

However, it’s YOUR gun. If you want to let it cool, it’s precisely zero skin of of anybody else’s hindquarters. Worst that’ll happen…

[scene]
Shootin Buddy 1: Y u no shoot more now?

mattm0812: Lettin gun cool

Shootin Buddy 1: Shit me???

mattm0812: Shit u not

Shootin Buddy 2: He from benchrest background

Shootin Buddy 1: Aaaaawwwww…cute! pats your head
[/scene]

That was a dramatization. Any resemblance to real events or real people is coincidental. No animals were harmed…

Usually, if the thing’s heated up enough to the point that accuracy is affected in a way one can tell, without instrumentation (…which bench guys USE…!), the POI shift is predictable…presuming you’ve shot the thing to that point, several times, and noted the trend. Think of the differences one might see suppressed/unsuppressed. Similar effect, though it’s like watching a spot of oil on your shirt spread; gradual, instead of on/off like a light switch.

15

We “acquired” a full auto lower in Iraq, which we promptly took to our range and began passing it around to slap on our uppers. We had barrels turning white. The very same day I qualified expert with the same barrel. You’re good to go. It will handle muuuuch more than you can throw at it.

16

If there are internal stresses in the barrel, heat can cause a shift in POI. The shooter will see this as stringing.

Heat can also have an affect on barrel harmonics and groups can open up. (They can shrink also, depending on the barrel.) Group size will change but remain round.

Heat can affect powder burn rate. A chambered round will warm up and cause a slight rise in velocity. The longer the round is in the hot chamber, the greater the rise. This will be seen as vertical stringing. It is also dependent on the powder used.

It’s up to each shooter to find out what affect heat has on their groups and why