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quote:
Originally posted by SgtGold:
[

I agree with RHINOWSO on this one. The heart of any rifle is the barrel. If the rifle is for self defence then it better be hammer forged 4140 and both MP and HP tested. 4150 is what the military uses, but the extra cost will only help if full auto is in your future. The following is a pretty good article on the subject.

https://gunnewsdaily.com/best-ar-15-for-the-money/



I don’t know of anyone making 4140 barrels with CHF. 4140 tends to be used by lower tier manufacturers.

CHF is nice but not a necessity. Consider the fact that a 16” 4150 cmv barrel will last 10k rounds, possibly more when fired semiauto and not suppressed. 10k rounds cost roughly $3k. Most people won’t shoot 10k rounds in their lifetime. Even most PDs prob put a couple hundred rounds through each rifle annually.

I personally prefer CHF in my rifles. But I have a bunch of uppers with button rifled chrome lined 4150 CMV barrels, all Colt and LMT, three of which see frequent fullauto suppressed fire. One of my LMT 10.5s has nearly exclusively seensuppressed FA fire and it’s at the 8-9k mark, still ticking. I did swap out the bolt for good measure at 7k.


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"AND YEA THOUGH THE HINDUS SPEAK OF KARMA, I IMPLORE YOU...GIVE HER A BREAK, LORD". - Clark W. Griswald
 
Posts: 1955 | Location: The South | Registered: September 12, 2005Reply With QuoteReport This Post
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quote:
Originally posted by striker1:
I’d expect a nitrocarburized barrel to go 20,000 rounds. A stainless barrel would wear faster. I’ve no idea on the double-chromed CHF barrels, but perhaps 30K or more? Depends largely on the type of shooting.

quote:
Originally posted by JoshNC:
CHF is nice but not a necessity. Consider the fact that a 16” 4150 cmv barrel will last 10k rounds, possibly more when fired semiauto and not suppressed. 10k rounds cost roughly $3k. Most people won’t shoot 10k rounds in their lifetime.


Barrel life is a factor of how rapidly one shoots, how hot the barrel gets, the type of steel in the barrel, whether or not the barrel is lined or treated, and the accuracy requirements for given target distances.

It's my understanding that Camp Perry competitors expect 3k to 4k rounds before they retire barrels.

On the other end of the spectrum, barrel life for a rifle expected to hit the thoracic cavity at 30-50 feet will be quite long. With such accuracy requirements the barrel might not have any lands, the throat area will look like a dried mud bed, and the bullet might keyholing on the target. But the gun will still go bang and the bullets will still impact -- possibly with tens of thousands of rounds down the pipe.

I retired my first AR15 barrel at 4,800 rounds. It was a 16" Wilson Combat SS 1/9 mid-length. The gun shot most match ammo at 1 MOA or less, but really shined with FGMM 69, with which it was a 3/4 MOA barrel. A bad day (meaning I was shooting like dog doo) with that combo produced 100 yard groups of 1.1" or 1.2". Over the one day's practice, the barrel began showing a lot of vertical dispersion. Not too bad at 100 yards, as 1 MOA to 1.25 MOA was still the rule. But at 400 to 500 yards the vertical increased to 2.5 to 3 MOA with FGMM 69, with the odd shots going low. I pulled the barrel. I did not measure muzzle velocity, but I suspect there was a noticeable loss of MV.

I now have another AR15 barrel at 4,200 rounds which is likely at end of useful life. It's an 18" Wilson Combat 1/7 rifle-length. Two weeks ago it shot as expected out to 550 yards. At last weekend's match it dinged 400 yard steel without issue the first day, but I couldn't hit two 400 yard steel targets at the end of the second day. Which dropped me one place in the match standings. I shot it a couple of days ago to determine WTF was going on. Based on point of impacts at 340, 455, and 512 yards, MV with Hornady 75grain has decreased from 2650 fps to 2575-ish. I didn't bring the chronograph to test MV that day, but I will do so next time out.

The decrease in MV of this 18" barrel means POI is 1 MOA lower than my dope cards show at 450 yards. Given that I was shooting at 2 to 2.5 MOA targets in wind, I had limited ability to hit those targets unless I could spot low impacts. With wet brush and grass behind the targets, even my spotters couldn't see misses.

Understand that this 18" barrel is still pretty accurate. At 100 yards I just produced 5-round groups of .76" (cold bore & cold shooter), .83", .53", and .38". Because I shoot in noticeable crosswinds, I measure only vertical variation at longer distances. At 455 yards I had targets with vertical dispersion of .65 MOA and .40 MOA. At 512 yards the vertical dispersion on targets were .78 MOA and .53 MOA and .73 MOA. But the impact locations were lower than expected, and they will likely continue to drop lower again.

Bottom line -- effective barrel life can be quite different from one shooter to the next.
 
Posts: 5916 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
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PSA just dropped their cheapest build kit to $260 shipped. They also have lowers for $40 so if you live near one (no xfer fee) you can get a complete AR for $300 + tax. Ridiculous!
 
Posts: 926 | Location: Upstate, SC | Registered: March 19, 2008Reply With QuoteReport This Post
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