AR15 Barrel Life?
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ugaarguy
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Depends on the specific alloy, style of shooting (primarily rapid fire vs. primarily slow fire - this affects bbl. temp), sustained fire (or not), etc. There are several variables. I think for 4150 without hard chroming or nitriding it's around 4k rounds of sustained full auto fire to kill a 5.56 bbl.
You got it!
madcratebuilder
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For the typical AR user expect about 15K before you start seeing a lot of flyers. If you are competing and have a precision barrel then you are looking at about 5K before accuracy falls off. Throat erosion happens before you see the lands and grooves give up.
chrome_austex
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Yeah, handloaders that demand the highest accuracy may replace a barrel when the throat erosion makes it so that the handloader can no longer seat bullets far enough out to touch the lands.
Also, heavier bullets and faster twists will wear faster. Shooting 80 grain bullets at max pressures will wear a barrel a lot faster.
My HBar 1/8 twist chromoly match barrel has probably 7k through it and still shoots MOA with mag length handloads, but the throat has eroded quite a bit. Most of those rounds were reasonable 69gr and 55gr loads. I'll probably use this one for many thousand more rounds before I retire it. YMMV.
Also, heavier bullets and faster twists will wear faster. Shooting 80 grain bullets at max pressures will wear a barrel a lot faster.
My HBar 1/8 twist chromoly match barrel has probably 7k through it and still shoots MOA with mag length handloads, but the throat has eroded quite a bit. Most of those rounds were reasonable 69gr and 55gr loads. I'll probably use this one for many thousand more rounds before I retire it. YMMV.
kwelz
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There are BCM and Noveske Barrels out there that I have personally seen with 10s of thousands of rounds through them that are still going strong.
FlyinBryan
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we have a couple of 4150 chrome lined barrels creeping up on 10,000rds that havent started falling off yet. (still less than an inch most of the time @100yds, 5sht groups )
Are you talking chrome lined or unlined?
I personally have a chrome lined S&W M&P15 barrel (1:9, FWIW) that has over 20k rounds through it. Predominantly fed by Brown Bear ammo (3MOA ammo), it still shoots the same as the day I bought it. Could there be some kind of slight opening up of the group going on? No doubt, but using the cheap ammo that I do, I wouldn't know - it is still happily serving its purpose as my beater all purpose rifle, and good enough to consistently whack 8" plates at 200 yards.
sansone
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yes heat will hasten metal erosion. If your handguards smoke or soften you may be degrading your barrel's accuracy
I have a Bushmaster carbine upper with chrome lined barrel that lasted about 10k rounds.
It spend most of it's life on the M-16 lower so it had to deal with a lot of heat.
I have a RRA rifle with chromoly barrel that is going past 12k rounds and it still shoots pretty well but it was only fired semi-auto.
It spend most of it's life on the M-16 lower so it had to deal with a lot of heat.
I have a RRA rifle with chromoly barrel that is going past 12k rounds and it still shoots pretty well but it was only fired semi-auto.
briansmithwins
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I'd be surprised if a 5.56 barrel (semi-auto) lasted less than 5k rounds or more than 30k.
From docs I've seen the loss of accuracy can be very sudden. Rifle shoots normally than in the space of one mag the group opens up to 12MOA or better.
BSW
From docs I've seen the loss of accuracy can be very sudden. Rifle shoots normally than in the space of one mag the group opens up to 12MOA or better.
BSW
I think this is a non issue and not worth worrying about. By the time you burn out a barrel shooting semi-auto, the cost of replacing the barrel is going to be a drop in the bucket compared to the cost of the ammo that it took to burn the barrel out.
If you are just asking for the sake of curiosity, it's hard to answer your question. The number of rounds fired must be considered in light of the manner in which they were fired. Doing repeated mag dumps will accelerate the wear on the barrel.
Still, just as a point of reference, my beater carbine with a plain ole Bushmaster chromelined barrel has over 10K rounds through it and it still shot MOA or so with good ammunition the last time I pulled the ACOG off of it and used a bigger scope to see what it would do. I rarely do mag dumps, but do shoot it fast when I work on multiple target practice.
If you are just asking for the sake of curiosity, it's hard to answer your question. The number of rounds fired must be considered in light of the manner in which they were fired. Doing repeated mag dumps will accelerate the wear on the barrel.
Still, just as a point of reference, my beater carbine with a plain ole Bushmaster chromelined barrel has over 10K rounds through it and it still shot MOA or so with good ammunition the last time I pulled the ACOG off of it and used a bigger scope to see what it would do. I rarely do mag dumps, but do shoot it fast when I work on multiple target practice.
Depends on your definition of accuracy. Bench rest shooting with out cooking the barrel, I would put it up to 10k rounds before you may swap the barrel, perhaps a couple thousand less.
Military style thin contour barrels? I replaced barrels occasionally in the Army. Your looking at combat accuracy (as mentioned just smacking a plate at 200 yards for example) starting at 10k rounds in normal fire, up to about 20k plus. I have seen some barrels that were beat on hard give up throat erosion gauges at about 10k. I've seen others go to about 30k before the throat erosion gauges failed the barrel. But that is a significant amount of ammunition more than the lifetime of most shooters in a rifle. When the accuracy falls off beyond your acceptable standards is the time to swap barrels.
And by the way half of those rifles that failed throat erosion gauges? Still were used to qualify and shot well enough to do that and zero the rifle. Though I have seen one that the erosion gauge dropped half way down the barrel what was brought in because the rifle was keyholeing the green tip ammunition at 25 meters. Perfect side silhouette holes on the paper.
Military style thin contour barrels? I replaced barrels occasionally in the Army. Your looking at combat accuracy (as mentioned just smacking a plate at 200 yards for example) starting at 10k rounds in normal fire, up to about 20k plus. I have seen some barrels that were beat on hard give up throat erosion gauges at about 10k. I've seen others go to about 30k before the throat erosion gauges failed the barrel. But that is a significant amount of ammunition more than the lifetime of most shooters in a rifle. When the accuracy falls off beyond your acceptable standards is the time to swap barrels.
And by the way half of those rifles that failed throat erosion gauges? Still were used to qualify and shot well enough to do that and zero the rifle. Though I have seen one that the erosion gauge dropped half way down the barrel what was brought in because the rifle was keyholeing the green tip ammunition at 25 meters. Perfect side silhouette holes on the paper.
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