10 inch AR's: 7000 round barrel life?

Clobbersauras

Clobbersauras

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I found an interesting little study that was done on 10.3" barreled AR's. 4 rifles were tested, shooting 10,000 rounds each. All rounds were fired in short and medium length bursts.

Major findings:
-Major throat erosion occurred in all rifles between 7k and 9.9k rounds.
-Mean rounds between stoppages: 738
-Parts breakage consisted of an extractor, extractor spring, and three gas tubes. All breakages occurred between 6.3k and 9.1k rounds.
-Three of the rifles experienced significant loss of accuracy after 10k rounds.

I'm assume FA testing would accelerate throat and gas port erosion? But, based on this test and my current typical usage of my rifle, it looks like I have about a year before I should replace some small parts, and a little more than a year before I need a new barrel.

Study can be found in section 6 of this link:
http://www.dtic.mil/ndia/2003smallarms/2003smallarms.html
 
I doubt you are firing bursts or strings of more than 10 rounds...

You are probably good for almost double the life span before you experience similar wear out of a chromed bore. Say 15-18,000 rounds...
 
Very interesting. Almost no measurable wear or accuracy loss till after 3000 rounds. I would have thought things would go downhill faster than that at those rates of fire. My range guns are good for a few years still!
 
Petrock said:
Semi auto fire is not half or even 20% of the wear exhibited by auto firearms. I'm sure you have years left to abuse that barrel.
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Does anyone have any hard data to confirm this? I'm sure you a right but, would like to know what to expect down the road.

For their test, barrel temps were kept below 1000 deg F. The rifles were cooled and cleaned after every 300 rounds.

I was surprised that the gas tubes failed so frequently.
 
they are firing 4-6 round bursts and 2-3 round bursts in the 300 rounds cycle. You don't expect to fire 6 round bursts with a rifle - that's the LMG's job.

For the LMG or SAW, it got a hammer forged barrel with a steel that meets a 10,000 round firing test. They were firing these upper using almost the same testing for the M249.

What is the lesson here? If you want to use your CQBR this way, use better steel for the barrel and better gas tube - but a rifle is never envisioned to be used this way.
 
Clobbersauras said:
Does anyone have any hard data to confirm this? I'm sure you a right but, would like to know what to expect down the road.

For their test, barrel temps were kept below 1000 deg F. The rifles were cooled and cleaned after every 300 rounds.

I was surprised that the gas tubes failed so frequently.
Click to expand...

Gas tube failure sounds like a result of full auto fire. If I had to guess I would think one of our range ARs that never gets that hot would be fairly safe to at least 20K rounds with a good quality barrel. Even if accuracy degraded abit and the lower got abit sloppy, its probably still good enough for any other normal use.
 
Are you actually shooting a 10" barrel? because if not it will probably last longer...

And you dont typically burn though gas tubes on a semi-auto (unless somethings wrong or its REALLY OLD or it has some rust/corrosion issues)... At least not on a 7" like mine.
 
For their test, barrel temps were kept below 1000 deg F. The rifles were cooled and cleaned after every 300 rounds.
Click to expand...

You will NEVER get your barrel even close to that kind of temperature with our pinned mags. It is the heat that accelerates the erosion.

By the time you get an AR barrel to 1000F the gun is so fricken hot it is near impossible to hold on to. Steel begins to glow at about 1200F.

When we did some temperature testing on muzzle devices we never even hit 1000F on the barrel and the guy shooting the gun said the buffer tube was hot to the touch. He had to wear heavy leather gardening gloves to protect his hands on the free floated, vented forend. The upper was too hot to touch. The gun was essentially at the point of being unfireable because nobody wanted to handle it due to the heat.

I think that the report you read is a moot point when applied to civlian shooters in Canada.
 
Guys, I get it, FA is not the same as SA shooting in terms of wear and tear on the firearm. So what's the general consensus? Should I double the round counts found in this test or even triple them to use as an indication of expected barrel wear?

I shoot about 300 rounds per month out if my ten incher:D:cool:. If I took a safe guess and doubled the barrel life of what is found in this test to 15k rounds, I should probably replace the barrel in about 4 years. That is fairly acceptable to a low volume shooter like me.

If you are a high volume shooter, which some on this board are, you could be replacing barrels every couple years. It's something to consider when purchasing an SBR.
 
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I think the perceived, subjective advantages of the shorter barrel more than makes up for the possibility of having to replace the barrel sooner.......
If you're a high volume shooter, then you're going to be burning through crates of ammo, and even if you reload, the cost of the barrels is going to pale in comparison to the cost of the ammunition.
 
foxbat said:
I think the perceived, subjective advantages of the shorter barrel more than makes up for the possibility of having to replace the barrel sooner.......
If you're a high volume shooter, then you're going to be burning through crates of ammo, and even if you reload, the cost of the barrels is going to pale in comparison to the cost of the ammunition.
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That's exactly it. By the time you've spent 7-10k on ammo, you'll need to spend 300 bucks on a barrel, maybe 100 on parts. Small potatoes.
 
You need to change the barrel when either: the groups become patterns or the bullets pass through the target sideways (key hole) or you can't hit a target anymore from 25 feet. This will let you know when to change out.

An article about barrels on F/A guns that you can't own are insignificant.
 
Clobbersauras said:
Yes, it's a 10.25".
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Nice

Clobbersauras said:
Guys, I get it, FA is not the same as SA shooting in terms of wear and tear on the firearm. So what's the general consensus? Should I double the round counts found in this test or even triple them to use as an indication of expected barrel wear?

I shoot about 300 rounds per month out if my ten incher:D:cool:. If I took a safe guess and doubled the barrel life of what is found in this test to 15k rounds, I should probably replace the barrel in about 4 years. That is fairly acceptable to a low volume shooter like me.

If you are a high volume shooter, which some on this board are, you could be replacing barrels every couple years. It's something to consider when purchasing an SBR.
Click to expand...
Here's the thing... I've had barrels that came from the same batch, which were shot under the same kind of conditions... After a barrel starts to approach the 2MOA mark (for something I care about accuracy), I tend to replace the barrel and sell the old one (people often dont mind a 2MOA barrel if its a good price). Sometimes one barrel will go 15-20k rounds, sometimes another barrel from the same batch will go even longer.

Frankly, It's just hard to say... The best you can do is throw out an estimate based on your experiences... Then also it depends on how accurate is acceptable... Are you okay with 2MOA, 4MOA? What if it was 8MOA? Whats acceptable? It depends on the distances at which your shooting.

Listen, if you want the barrel to last a long time:
  • Don't go FA or use a burst activation device
  • Don't over clean the barrel


foxbat said:
If you're a high volume shooter, then you're going to be burning through crates of ammo, and even if you reload, the cost of the barrels is going to pale in comparison to the cost of the ammunition.
Click to expand...
Exactly... Barrels are cheap... You go though barrels, extractors, buffer springs, firing pins, etc... It is what it is...

But, all of those costs are nothing compared to the cost of ammo.
 
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