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Centerfire Rifles - Semiautomatic or Gas Operated Centerfire rifles, carbines and other gas operated rifles.

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  #1  
Old 03-21-2011, 2:25 PM
Rock_Islander Rock_Islander is offline
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Default What is the average life-span of an AR Chromoly steel barrel (non chrome-lined)?

Anyone know how many rounds my chromoly AR-15 barrel will last? It's a match grade bore and chamber, of chromoly 4140 steel.

I've put a little over 1500 rounds through this particular rifle (upper/barrel) and I've heard figures ranging from 10,000 to 18,000.

Just want to know when it'd be best to replace it on average. I know that groups may open up later down the road, and that might be when I should look into a new barrel, but I was wondering if anyone knew off-hand what I should expect.
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Old 03-21-2011, 2:59 PM
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The leades wear out first and that is what bench rest shooters refer too as "shot out" this is a progressive thing that you can start to see as low as 6k.

Really it will shoot for many thousands of rounds but you will constantly be wearing it and the accuracy will continually suffer until you replace it. When depends on many more factors you listed, how hot the loads are, your cleaning routine, how hot the barrel got from shooting.

So not to not give you an answer but it depends.
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  #3  
Old 03-21-2011, 3:01 PM
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Replace it as soon as You shoot it out. Your groups will not open up too much before keyholing starts and accuracy goes right out the window. I shot out a chrome lined 5.45x39 barrel at 12,500 rounds (all 7n6). I would expect double that shooting lead ammo. It is like a light switch, not a gradual loss of accuracy.
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Old 03-21-2011, 3:09 PM
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Quote:
Originally Posted by Nathan Krynn View Post
The leades wear out first and that is what bench rest shooters refer too as "shot out" this is a progressive thing that you can start to see as low as 6k.

Really it will shoot for many thousands of rounds but you will constantly be wearing it and the accuracy will continually suffer until you replace it. When depends on many more factors you listed, how hot the loads are, your cleaning routine, how hot the barrel got from shooting.

So not to not give you an answer but it depends.
yup, the speed at which you pull the trigger, and how often. A weekend 1000 round carbine course is the same wear as 3000 bench shots... thats just pulling numbers out the butt, but others have backed that up. You can expect less then 1/2 the life span if you are constantly mag dumping.

6K life for accuracy shooting Sub MOA
10K life for Hunting accuracy past 150 yards MOA
20K life for less than 100 yard shots, less then normal MOA
25K life for 50 yard with less normal MOA.

I have shot a barrel that grouped 5 inches at 50 yards...hahaha had like 40K rounds down range. Thats just 1 inch more then an new AK47
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Old 03-21-2011, 3:30 PM
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Thanks for the input guys. One thing I'm confused about is that Nathan Krynn said that it will gradually wear and lose its accuracy, whereas Rattlesnake says it's more instant like a light-switch. Am I misunderstanding or are there two different views on accuracy loss due to barrel wear?

Also thanks a lot for the general figures dieselpower. I really do a lot of shooting at 50-yards, and a fair amount at 100-200 yards as well. Those are my main distances at which I want my rifle to be fairly accurate at for X-amount of time.

Heat does destroy a barrel faster though? Even for chrome-lined bores?
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Old 03-21-2011, 4:04 PM
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10,000 out of a stainless or chrome moly barrel. Accuracy drops a lot past 7,000. Chrome-lined guns can last up to 20,000 BUT I'm sure accuracy is on a last leg. Remember to change your bolt at 10K rounds
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Old 03-21-2011, 4:52 PM
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Personally, I wouldn't worry about it unless you plan on blasting hundreds of rounds daily.

The 2-3 times to the range a month, ain't gonna do it. Shoot it, and forget it.
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Old 03-21-2011, 4:56 PM
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Quote:
Originally Posted by Army View Post
Personally, I wouldn't worry about it unless you plan on blasting hundreds of rounds daily.

The 2-3 times to the range a month, ain't gonna do it. Shoot it, and forget it.
This!!!just shoot it and don't mind it!
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Old 03-21-2011, 5:14 PM
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Quote:
Originally Posted by Rock_Islander View Post
Thanks for the input guys. One thing I'm confused about is that Nathan Krynn said that it will gradually wear and lose its accuracy, whereas Rattlesnake says it's more instant like a light-switch. Am I misunderstanding or are there two different views on accuracy loss due to barrel wear?

Also thanks a lot for the general figures dieselpower. I really do a lot of shooting at 50-yards, and a fair amount at 100-200 yards as well. Those are my main distances at which I want my rifle to be fairly accurate at for X-amount of time.

Heat does destroy a barrel faster though? Even for chrome-lined bores?

@ 2000 rounds a year, you are looking at a barrel every 10 years. As long as you dont feed your family by shooting 5 holes under 1" apart... no worries.
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Old 03-21-2011, 5:30 PM
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+1 I can only speak from my experience. I have never owned a chrome molly barrel, or shot out any other barrel besides the 5.45x39 with 7n6. It shot accurate right up until it was shot out. It really was like a light switch. I was like WTF??? So I threw a smith vortex on there, and still keyholing, and major stringing. Replaced the barrel for the cost of a tin of 7n6, and I'm rocking and rolling again. FWIW there was no noticable damage to the crown. The rifling looked a little rounded I guess but nothing that one could look at and say, "that's a shot out barrel". I wouldn't worry about it til I shot it out, unless my life depended on it. You can always buy one and save it for a rainy day, but I bet You will get the itch to just build another upper with it after a few years lol.
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Old 03-21-2011, 5:33 PM
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Quote:
Originally Posted by dieselpower View Post
I have shot a barrel that grouped 5 inches at 50 yards...hahaha had like 40K rounds down range. Thats just 1 inch more then an new AK47
LOL. Aint that the truth!
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Old 03-21-2011, 6:02 PM
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Quote:
Originally Posted by rattlesnake_nm View Post
+1 I can only speak from my experience. I have never owned a chrome molly barrel, or shot out any other barrel besides the 5.45x39 with 7n6. It shot accurate right up until it was shot out. It really was like a light switch. I was like WTF???
Most likely, the accelerated wear came from shooting corrosive ammo and not cleaning right away. Next shooting session simply blew out the rust that formed.
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Old 03-21-2011, 6:08 PM
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Actually, it was cleaned immediately after every session, and I live in a very low humidity climate. I think it had more to do with steel bullets.
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Old 03-21-2011, 8:46 PM
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Quote:
Originally Posted by Rock_Islander View Post
Thanks for the input guys. One thing I'm confused about is that Nathan Krynn said that it will gradually wear and lose its accuracy, whereas Rattlesnake says it's more instant like a light-switch. Am I misunderstanding or are there two different views on accuracy loss due to barrel wear?
...
For my AR, I noticed it when shooting one (new) brand of ammo. The one brand would keyhole where the others would not. Then when I was testing it out on paper targets / bench, it was starting to become noticeable (larger groups and keyholes) at the longer distances with the old ammo brands. It still grouped OK at 50 yards (and knocked over cans / bowling pins) with the old ammo but the new ammo was keyholeing and having problems hitting the cans/pins.
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Old 03-21-2011, 9:31 PM
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Thanks for the input gentlemen!

Do you guys have a gunsmith replace your barrel(s) or do you do that yourselves at home? Ideally I would like to get set up in my garage for that type of job... Because there are almost NO gunsmiths here in the Northern California region that will smith' AR type rifles. It's sad. But it's the reality.

And does anyone know how to remove a "smooth" type free float forend from AR's? I've heard they're bonded on the FF barrel nut with some sort of locking compound. I'm asking because my rifle with the chromoly barrel, has a free float forend that is of the "smooth" type.

What about removing an AR barrel in general? Anyone with knowledge of how to do this at home?
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Old 03-22-2011, 6:47 AM
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I've put together a handful of uppers now using the clamshell-style receiver block and a cheap AR multitool (not a very good fit) for the barrel nut. I also have a tool to lap the upper receiver square to the bolt travel where it mates to the barrel, AFAIK didn't do diddly squat for increasing the precision of a $200 barrel. You'll need to remove the gas tube before you can spin the barrel nut, and might want to buy a new gas tube and roll pin as well as a new bolt. If you decide on a threaded barrel you'll also need a new crush washer to allow you to index the flash hider or whatever in the correct orientation to the rifle.

For your free float, can't help. Personally I'd try those rubber oil filter strap wrenches right over the barrel nut using plenty of painters tape to prevent marring, but yeah no experience really. Actually I think you'll need a special wrench for that barrel nut and can't go the cheezy multitool approach.
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