Approximately how many rounds can be fired through an AR 15 before the barrel must be replaced? I have heard that the S&W M&P Sport models only last about 5000 rounds before the grouping start spreading out while your midpriced $1000-$1300 AR will last about 10,000 rounds.

Any opinions or information or data would be helpful. Thank you and happy shooting.

I don't know the magic round count, but in what manner it's fired will make a difference. Is the barrel heated up from consistent fast firing or it it shot more like a hunting rifle with time to cool between shots or short strings. You might notice a loss in bench rest accuracy after 3,000 to 4,000 shots in a top level target gun, but I'd think the average AR user might get well over 20,000 rounds with little noticeable accuracy loss if the barrel isn't abused.

S&W has said 7k-10k rounds.

It all depends how you treat it and ammo and other factors as well.

Ammunition type, rate of fire (heating of the barrel), and other factors come into play.

But do the math - I'd estimate it's about 10K-20K for a 'normal' user - 10,000 x 0.30 cents per round.

$3000 in ammo (low end 10K rounds) / $6000 in ammo (high end 20K rounds)

So I think if you can spent $3-6K in ammo, another $200 barrel is easy to stomach (ie, you don't need to replace the whole "rifle", just the barrel and maybe the bolt / BCG - the upper, lower, stock / rails will be fine).

quote:

Originally posted by RHINOWSO:
Ammunition type, rate of fire (heating of the barrel), and other factors come into play.

But do the math - I'd estimate it's about 10K-20K for a 'normal' user - 10,000 x 0.30 cents per round.

$3000 in ammo (low end 10K rounds) / $6000 in ammo (high end 20K rounds)

So I think if you can spent $3-6K in ammo, another $200 barrel is easy to stomach (ie, you don't need to replace the whole "rifle", just the barrel and maybe the bolt / BCG - the upper, lower, stock / rails will be fine).

Good point Rhinowso, I like your math.

Materials influence it as well...

Stainless steel won’t last as long as CHF.

Non chrome lined won’t last as long as chrome lined.

A reasonable question with many possible correct answers. The first part of the answer is what do you do with the rifle and what is your accuracy expectation? Some high level master class high power competitors will replace a barrel in as little as 3-4 thousand rounds.the tactical tommy types ( no offense to anyone!) who generally use rifles on man size targets inside 300 yards may be able to go 5-10 times as much prior to accuracy becoming unacceptable for that purpose. My little AR barrel story is my brother got a Colt that had been in a flood and the barrel despite the chrome lining still had some rough spots. A number of years of relentless abuse ( limited cleaning, run it till the barrel smokes play with a Gatling gun crank etc. ) resulted in bore erosion to the point the first couple inches of the the barrel and last couple inches of the muzzle were essentially smooth bore! Just prior to replacement he shot a five round bench group at 100 yards that held just under 4 inches.
There is no set number some barrels will show degradations in accuracy in 3k others hold for 30k no rhyme or reason

^^^ I’d be interested to know how the last couple inches got eroded towards the muzzle. I didn’t know that was a symptom of a high round count.

Rate of fire and how hot the barrel gets is more important than round count. The rack grade rifles we used in matches were never fired in burst or full auto. As Rhinowso said, if you can afford to wear a barrel out you can certanly afford to replace it. To me barrel life in any firearm is a non issue.

I know it depends on many conditions and also what kind of barrel you start with. But as a data point I often buy used barrels from a few friends of mine who are high power shooters and they have generally have had 3-4K rounds on them. I don't actually know if they do the replacement because they see degradation or its predictive before problems happen. I've no trouble with using those barrels and commercial ammo for acceptable range accuracy. Again on a personal note my 6940 has 10K rounds through it and I've not noticed any issues.
All FWIW>
j

Ok, so I need to keep somewhere between 5-20K rounds per AR.

quote:

Originally posted by SSAreGreat:
Approximately how many rounds can be fired through an AR 15 before the barrel must be replaced?

That's the $64,000 question. There are lots of answers & suggestions, many of them are correct for a given set of parameters.

Few barrel manufacturers will give an answer to 223 barrel life. Lilja suggests accurate barrel life of 3k to 4k rounds, with varmint accuracy a little longer. Lilja is likely referencing a bolt action barrel used for long distance and high accuracy.

Criterion states 10k to 20k rounds are possible, while still retaining a great deal of accuracy and muzzle velocity. They say some 3-gun competitors are getting 17k to 19k rounds of limited volume stages on their barrels. On the other hand, high power & service rifle shooters are getting 3k to 6k rounds.

For those competitors interested in maintaining the highest accuracy, I've heard 4k to 6k rounds is all a shooter can expect. The barrels aren't "toast" to many people at this point, but they are no longer competitive -- especially at distance.

Lucky Gunner did an interesting test on ammo types -- steel cased & bi-metal bullets (Russian cheap ammo) versus brass cased & copper bullets (American Eagle FMJ). The steel cased & bi-metal bullet ammo really did a number on the ARs, but the AR using AE was still chugging along at 10k. Google "brass vs steel cased ammo" or Lucky Gunner. It's worth the long read.

I believe the Army accuracy requirements for an M4 with FMJ ammo is in the 4-5" ballpark at 100 yards. This gives a lot of leeway to guns/barrels/ammo combinations, and I think their expected service life for a barrel is in the 10k ballpark.

I personally have no interest in a rifle/ammo combo with 4-5 MOA capabilities. Hell, even 2-3 MOA capabilities are unacceptable in my book. I don't have my log book with me now, but my 16" carbine has between 4k and 5k rounds on the barrel. It's still shooting well, but not up to the accuracy of my longer barrel rifles, which have newer barrels. For my accuracy demands, the 16" barrel is getting close to retirement age. Maybe this winter I'll figure out when to pull the barrel. At that time I will upgrade optics and move the carbine into a more intermediate-distance sorta-precision role.

Some ways to test when a barrel is toast:
- bore scoping
- measuring the chamber with gauges
- maintaining accuracy logs, then looking for deterioration
- maintaining muzzle velocity logs, then looking for decreased muzzle velocity
- observing accuracy at distant targets, then looking for unexpected flyers -- especially low impacts

^^^^^^

Good info.

Thanx fritz

High Power barrels are graded on 600 yard accuracy. The highest round counts I've personally seen are an M-1A that was at 8,500 rounds and still holding the 10 ring at 600 yards, and an AR-15 with about 6,500 rounds and still shooting at 600 yards. These numbers are on the high end of normal. What happens to a barrel is the throat becomes shot out, and the bullets are no longer constantly entering the rifling round to round. Many shooters take the now 'shot out' barrel and use it for 300 yard or shorter reduced course matches.

Here's a link to a rifle that Pat Rodgers used as a loaner for students taking his courses. It's a 16" Bravo CO carbine nicknamed 'Filthy 14'.

http://www.slip2000.com/blog/s...-magazine-filthy-14/

FN publishes that the service life of the SCAR 16 barrel is 35,000 rounds which likely references an accuracy spec set by SOCOM. In the Battlefield Las Vegas thread on ARF.com they said the SCAR barrels reached well over 80,000 rounds run in full auto for their entire lifespan before they began to keyhole. So the 35,000 round service life for usable accuracy is probably pretty reasonable. I would imagine that the AR15 barrels FN makes that are CHF and chrome lined like the the SCAR barrels would see similar performance.

https://www.brownells.com/rifl...rrels-prod71548.aspx

It is my understanding that most of the shooting at Battlefield LV is done at an indoor range, on silhouette-sized targets at 15-20 yards. At such close distances, a full auto rifle could be shooting with "accuracy" of only 15 or 20 MOA and still produce tighter groups than most of the people renting their guns. The loss of muzzle velocity from throat erosion and the loss of accuracy from land erosion won't be noticed by Battlefield's clientele. A barrel has to be really worn out to keyhole at such short distances.

Sure, FN's barrels might actually launch a bullet at 35,000 rounds, with the ability to hit a big target at CQB distances. Assuming the gas port is still functioning, I suspect most AR barrels could technically still be functioning at 35k rounds, too -- as long as functioning is defined as allowing a bullet to exit the muzzle.

quote:

Originally posted by RHINOWSO:
Ammunition type, rate of fire (heating of the barrel), and other factors come into play.

But do the math - I'd estimate it's about 10K-20K for a 'normal' user - 10,000 x 0.30 cents per round.

$3000 in ammo (low end 10K rounds) / $6000 in ammo (high end 20K rounds)

So I think if you can spent $3-6K in ammo, another $200 barrel is easy to stomach (ie, you don't need to replace the whole "rifle", just the barrel and maybe the bolt / BCG - the upper, lower, stock / rails will be fine).

Also, to add to Rhino, not all barrel qualities are the same. A higher end barrel will last longer. A lower quality barrel may not last as long. SS barrels definitely do not last as long as chrome lined.

As a hobby, I've been keeping track of throat wear/erosion (TE) in my .224 and .30 bbls. I didn't start keeping .224 data until a few years ago as I didn't have a calibrated .224" TE gage, so I have more .30 data I can report and not as much .224 data.

At least from the 1940's into the 1970's the US military used TE gages to measure wear (30-06, 7.62x51 and 5.56) (I have no 50 cal experience), considering a bbl worn out when the TE reached 1". My experience owning a M1919A4 machine-gun was at 1" TE the 100yd machine gun "groups" at 100yd firing off a tripod within the next 250-500 (1 to 2 belts) would suddenly go from inches to feet. This was consistent with the 3 bbls I wore out in 30-06 (each unlined bbl also reached that point at 5000rds fired, normally shot in short bursts). Of course if a bbl I own no longer maintains the accuracy that I want, it will have been worn out regardless of TE measurement.

Generally, each new Blackout bbl follows the same path: Rapid TE wear in first few rounds followed by a long period of slow wear after it's broken in. I suspect the first few (10-50) rounds are simply removing any rifling burrs/high spots left from the manufacturing process (i.e. the bbl is being broken in). A hand lapped bbl does not show this initial rapid wear.

My favorite cartridge is the 300 Blackout, so I've been comparing the different bbl steels and bore treatments in that caliber. My Blackouts (about a dozen of them) are fired 5 shots and let cool to ambient temp before being fired again (I have a fan on the bbl at the range). The 5 shots themselves may be fired fairly quickly. In other words, I'm taking it easy on the bbls.

ASSUMING that a 300 Blackout is worn out at 1" TE and ASSUMING the slow wear period after break in continues at the same rate. Here's some calculated bbl lives for jacketed bullets:

In my Remington M700 16" 300BLK with non treated 4140 bbl, the calculated bbl life, so far, is 11,820 jacketed rounds.

In my Core15 9.5" 300BLK 416R SS bbl, the calculated bbl life, so far is 12,540 rounds.

In my Remington M7 Micro7 16" 300 BLK with nitrided 4140 bbl, the calculated bbl life, so far, is 13,697 jacketed rounds.

In my Daniel Defense 16" 300 BLK with nitrided CHF CMV bbl, the calculated bbl life, so far, is 14,190 jacketed rounds.

In my Daniel Defense 10.3" 300 BLK with nitrided CHF CMV bbl, the calculated bbl life, so far, is 14,650 jacketed rounds.

In my Robinson Arms 16" 300BLK with chrome lined 4140 bbl, the calculated bbl life, so far, is 16,740 jacketed rounds.

In my PSA 8" FN CHF CMV double Chrome lined bbl, the calculated bbl life is 22,667 rounds.

I have other Blackout bbls than listed above, but not as much data as on these bbls or the Blackout bbls are fired predominately with lead bullets. For example, I have 2 Ruger 4140 CHF no bore treatment bbls. In the limited data I have on them, they are showing less wear than the Remington bbl, but more wear than 4140 nitrided. Makes sense; CHF bbls are supposed to last longer than button or cut rifled bbls and nitriding is supposed to make bbls last longer. My PSA chrome lined (FN made) bbl is showing so little wear with such a long calculated bbl life that I recently added another PSA chrome lined (FN made) Blackout bbl to my testing to see if it wears the same...while I don't have as much data on it, so far it's showing the same very slow wear.

What I'm finding interesting, as Internet posts would not always agree, is that chrome lined Blackout bbls are wearing slower than nitrided bbls. I've made sure I have a 5.56 chrome lined 41V50 bbl, a 5.56 nitrided 41V50 bbl, and a 5.56 416R SS bbl to compare.

In 5.56 I also fire 5 shots and let the bbl cool. Exception: I have 3 bbls used in the M16, 2 chrome lined 4140 steel and 1 nitrided probable 4140 steel (on that last bbl SIG will not tell me the steel). I fire around 30 rounds full auto and then let the bbl cool, but not always to absolute ambient temp, after all, I'm having fun with the full auto. Even with my full auto firing, it looks like those 2 Model 1 Sales chrome lined bbls, (not a lot of data - 1204 rounds on one and 1839 on the other), may last a long time, as my 5.56 TE gage shows no wear so far after initial break in.

A few observations: 1) Lead bullet loads show about 1/3rd the wear of jacketed bullet loads in the Blackout and 30-06 (I suspect it's due to the bullet being softer and less powder being used). 2) Copper plated bullets show the same wear as jacketed bullets in the Blackout. 3) Most makers will readily tell me or advertise what rifle bbl steel they use. SIG refuses. 4) Ruger and Robinson Arms were very interested in my data and told me some of their data, which was matching mine. Ruger even offered to rebarrel for free if I wore one of their Blackout bbls out if I'd let them section the worn out bbl, keeping half and sending me the other half of the bbl...the Ruger American Rifle engineer was very nice to talk to.

Another calculated bbl life, based upon rounds fired and TE so far:

Ruger Precision, 4140 CHF, no bore treatment, all slow fire, .308 - 7,380 rounds

It's fun, I'm retired, and shoot at least 2 times per week. I can shoot at my club, on my farm, or at my neighbor's range just 2 miles away and have the combination to his gate lock. I work on reloading several times per week. My data so far makes sense in that harder bbl steel should last longer. CHF is supposed to last longer than not CHF. Bore treated bbls should last longer than plain bores. I use the TE method as it's easy to do. But, as I get more bbls (there's always an interesting gun or *project coming along) it dilutes the amount of time I can spend shooting any one bbl...oh well, it's fun.

* Interesting project recently completed: Using SIG MCX upper on M16 lower (the nitrided SIG bbl mentioned above).

Short video of that conversion: https://www.youtube.com/watch?v=ShZf87R9H4s

Keep up the good conversation. Really, for most people it's a non-issue, but for others it's interesting conversation.

quote:

Originally posted by Dae Zee:
ASSUMING that a 300 Blackout is worn out at 1" TE....Another calculated bbl life, based upon rounds fired and TE so far:

Interesting information on the 300 blk.

Assuming that the powder charge of 300 blk loads are roughly similar to those of 223, a 223 barrel will obtain 1" TE faster than the 300 blk barrel. I don't know what the conversion is, and I doubt there's a whole lot of apples-to-apples data out there yet.

Consider what occurs with 308-ish sized cases, based on the 1/2 to 3/4-ish MOA accuracy requirements that precision/tactical/steel match shooters demand from their bolt action rifles.
- 6mm bores (.243, 6x47 Lapua, 6 Creedmoor) may go 1500 to 1800 rounds before accuracy goes south.

-6.5 mm bores (.260, 6.5x47, 6.5 Creeedmoor) may go 2500 to 3500 rounds before accuracy is gone. I put 3200 rounds on my Creedmoor before I pulled the barrel.

-308 Win will definitely last longer, but few precision guys use this round anymore. Maybe 5k to 8k rounds before the required accuracy isn't there. My 308 is still doing well at something like 4500 rounds, but it seems to be getting a little picky about bullet type. For now I have decided to shoot only loads with SMK and Amax bullets. I'd like to do more testing of TMK and ELD bullets, but I will wait until I install the new barrel.

No standard of accuracy expected here, but...

https://www.ar15.com/forums/ar...ur-range/118-677135/