Just learned how to bump fire this weekend and got a little carried away. 3 30 round clips about as fast as I could shoot, and when I was done there was smoke from the burning CLP coming from under the handguards. Time for a new barrel, (it's a Colt M4 upper BTW) or no problems? Also, if this is not over the limit, how many rounds IS the limit before hurting the barrel?

I read somewhere the military is getting around 9600 rounds before seeing accuracy start to drop off.

Yes these are weapons that routinely shoot full auto.

I'm not sure you have to worry too much about a chrome lined semi auto rifle far in excess of that, click the link below, and scroll down.

[url]http://groups.msn.com/TheMarylandAR15ShootersSite/barrelfaq.msnw[/url]

The point is not whether you "hurt" the barrel,
but rather how much wear is acceptable.
An M4 type barrel is designed for Full Auto ,
which is more rds per second than you can bump.
(really it is )

In military usage , if you can hit a man sized
target at say 300 meters(with a M4 carbine)
that is acceptable.

Of course if all you do is bumpfire, it will
degrade more quickly than if used for aimed
fire.

You could probably bump off 20,000 rds
and still have a functional rifle , but you
couldnt hit a target at any great distance.

I am not worried about barrel life, I am worried that I got it to hot by shooting to many rounds to fast. Barrel life is for sure shortened by rapid fire, but how much rapid fire is to much?

That's what I said.

Nobody abuses barrels like the military, with full auto drills etc.....

If these guys are getting 9600 rounds out of chrome lined barrels before seeing problems, even while shooting full auto strings, I don't think you have much to worry about prior to shooting as many rounds.

One can't come near the sustained rate of fire from a semi auto, as a rifle on full auto or fast three round burst fire. No matter how fast you think you're pulling or bumping the trigger, etc.....

But heck if you're worried about it, keep a round count and replace the barrel at +/- 5000 rounds or so. That way you wont have to worry about it.

As for heat buildup per shooting session, this is a difficult question to answer.

If you start to see the barrel glowing red, or bullets seem to be going in all different directions downrange, you know its getting hot and are in danger of wearing it out or doing damage.

Me, if I can touch the barrel I don't worry about it. But then I save the rapid fire for when I really need it.

Besides that shoot heck out of it, if it makes you happy.

If it breaks or the barrel wears out you just buy you a new one.

As far as I know, (and I could be wrong), the military does not train to shoot full auto.  It wastes ammo and testing has shown that 3 rounds shot at full auto is the max # of rounds that can be fired before the effects of recoil negatively affect accuracy.  Hence, the theory behind 3-round burst.  

P.S.  I'm fairly new the AR world, I've never heard the term "bump firing".  What is that?

The life of a barrel ends when accuracy drops below 'YOUR' acceptable level.

Ok how about a barrel without chrome lining?
How long before it goes south? Anyone done any studies on that? Surly the Military has done some in the past with old A1's.[sleep]
I wish I know about this sight before I bought my AR 15 (DPMS)[pissed]

I spent $950 on my bushmaster XM-15 E2s before I found this sight.  Oh well it's a great gun and all of the next ones will be purchasd with the help of these forums.  
How in the hell can you bump-fire an AR?...  I can do it easily with the Ak but have never tried with an AR due to lack of recoil.

STANMAN, all you did was burn off some of your lubricant.  Bump firing will not hurt your barrel.  You will melt your gas tube before that happens, and for that to happen, we are talking lots and lots of mags as fast as you can fire, or perhaps a Beta C-Mag (100 rd drum) on full auto with some more full auto 30rd mag dumps after that, and even then all you have done is melt your gas tube.  When you fire a belt fed, continuously until the barrel goes past red hot, to white hot, and you start seeing the bullets through the barrel, then you will be doing some damage to your barrel, and even then if you cool it off, you are ready to shoot some more on full auto.  It takes a lot of continuous full auto fire, non-stop, when the barrel is glowing hot to hurt it, and in an M16/AR-15 that means your gas tube has long since failed, causing you to stop and just replace the gas tube.  After 5000+ rounds of full auto fire, then check your barrel.  My M16 barrels still look mighty fine, even after moderate abuse, much worse than bump firing.

The sustained rate of fire for the M16 AR15 family is approximately 12 to 15 rounds a minute. You also should not fire more than 140 rounds in a short period of time.
Pat

I'm trying to burn out my barrels. It will give me yet another excuse to get rebarreled on 14 Sept 2004!

I think your barrel is worn out already. You should ship it to me for proper disposal.[:)]

Ok what is dump firing mean anyway?[heavy]
Could you explain please? Pardone my ignorence!
[sleep][thinking]

Using one of those thermometers that read heat just by pointing it at an object, an M4 barrel will be around 550 degrees after dumping 210 rounds as fast as you possibly can on semi. It will also be real unpleasant to hold with M4 handguards. Cook-off starts to become a possibility after the sixth mag.

Throwing an eighth 30rd mag into the gun and going again will take the barrel temperature up to 725 degrees (96 degrees air temp) and will melt the glue on the heatshields of the M4 handguards as well as causing some really noxious smoke from burning glue.

They are doing some testing at the local range and need to fire 4,000 rounds on a regular (almost daily) basis. I'll ask them how their M4s are holding up to that; but last time I had talked to them about it (several months ago) they had only replaced two barrels - but they also weren't being very demanding about accuracy 10" groups at 100 and the barrel was still deemed OK.

Wel as of this reading my 7.5 inch Model 1 barrel is still hanging in there....Eats all ammo including wolf 223. Its on a RDIAS and has an un godly cycle rate , like 1000+rpm easily.

Now Its damn accurate for a 7.5 at 300 yards it still is accurate as anything I own. I just have to account for the bullet drop much more then others.

BUllet count is getting to 7K with about 1000 in .22LR

WIth that weapon I will be shooitng that barrel until the bullets come out sideways.

Interesting thing though. Sunday when I cleaned it I noticed my bore brush didnt spin much or at all while brushing the barrel......I can still see the lands and groves But i get the feeling that it is going to need replacing by 10K....we'll see. To me its just a room broom for CQB.

Bump-firing: This is my own definition, I've only done it once or twice and to anyone says bumping isn't as fast as an M16 hasn't seen a properly tuned "bumping" carbine. I've seen a carbine that was built JUST for bumping, light trigger, polished insides for a higher cyclic rate, it was amazing to see it take off.

Ok now for the definition, you drop the weapon to your hip putting your index finger (or thumb) through the trigger guard. You pull the rifle forward pretty hard and when you shoot that little amount of recoil drives the rifle backwards allow the trigger reset then your forward pressure drops the hammer again.

Brasspile and Tattoo can show you some bump-firing that will have you wondering if it's a full-auto.

Had a hammer forged, Chrome lined barrel that went from 1" groups at about 12k rounds to 4-5" groups at 15k rounds.  Throat was seriously eroded.

If you shoot 500 rounds in a summer, or even 1000, you're still looking at 10-12 years life out of your barrel.

NavyShooter

www.canadiangunnutz.com

[shock]Wow cool have to try it sometime!!
Thanks for info.[whacko]