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Posted: 6/5/2003 9:43:24 AM EDT
After quite a bit of reading, I've found a very large window on how many rounds you can put down range through your AR.

If I recall correctly, there was a SWAT mag article where the guy said he had around 80,000 rounds through his Oly Arms. From what I understand, these are not chrome lined.

I've read that a chrome lined barrel will last only a thousand or so rounds more than an un-chromed barrel.

I've read that a chrome lined will last around 30,000 and an un-chromed will last around 5,000 rounds!?!?!?!

I understand that the different types of ammo, and how many you consistently shoot at one time will affect life.

So.....can anyone shead some light on the truth about barrel life?
Link Posted: 6/5/2003 9:50:16 AM EDT
Ive seen moly-steel barrels with 5000 rounds through them that have 6in groups at 100yds. Ive also heard about M16A1s with 70k through them and they still have 2in groups. BTW Oly used or mabey they still do affoer chrome as an option on their shorts.
Link Posted: 6/5/2003 9:54:23 AM EDT
[Last Edit: 6/5/2003 9:56:57 AM EDT by Collin]
Sarge, I have a reply for you. The true answer is "it varies". Different people have different definitions as to what a worn out barrel is. Some people call the bbl. worn out if it no longer is capable of "X" moa accuracy. Others won't say it is worn out until there is no perceptible rifling left. Another tells wifey that his barrel is worn out because he really wants a new M4 profile barrel, if you know what I mean. Other factors include the type of ammo, how "hot" that ammo is, how often a barrel is cleaned, and many many others. I am still a relative [newbie] to AR rifles, but I do own a .22 rimfire with an estimated 25,000 rounds through it. That rifle is still wonderfully accurate from my point of view, but a benchrest shooter would say the barrel sucks and is worn out. So, there is no true answer to the question, except on an individual basis. Tell us what a worn out barrel means to you, and maybe some of our gurus can help out.
Link Posted: 6/5/2003 10:09:19 AM EDT
In an article posted last week here a 20" HBAR barrel lasted 12,000 rounds before the bullets started keyholing. Although I wonder how the test itself affected the barrel lifespan. The test involved firing round after round and I would suspect that the heat involved would contribute to barrel life expectancy.
Link Posted: 6/5/2003 10:13:48 AM EDT
Well, my 1911 has at least 30k rounds through it- the rifling looks like hell and would not pass muster by most gunsmith's standards. However, it still shoots much tighter groups than my Glock which only has 2500 rounds through it. Does that mean the 1911 needs a new barrel? (Or maybe the Glock?). IMHO, if you can't tell the difference, then the rifle is still good to go, also known as the "the weapon can shoot better than I" theory. You will never find two people to agree on this issue. Also, be careful of the chrome lined vs. non-chrome lined issue- this is an issue ripe for a flame war. My uneducated guess is unlined will go about 10,000 rounds or more, chrome-lined maybe 25-50% longer. But once again, that is just my uneducated guess and what I am comfortable with. Those of us w/o chrome lining in our weapons are apparently second-class AR citizens [;)]
Link Posted: 6/5/2003 11:02:03 AM EDT
[Last Edit: 6/5/2003 11:02:28 AM EDT by Thomas_A_Anderson]
80,000 rounds through an Oly? What about all the "experts" here that say Olys are junk that will no doubt self destruct in short order???[;)]
Link Posted: 6/5/2003 11:32:27 AM EDT
Sarge, As pointed out it varies, based on ammo used (was it hot?), type of shooting (slow single shots, fast semi-auto, full-auto), and how it was taken care of. Never forget to throw in the materials variances or what you consider to be 'acceptable accuracy'. Given identical conditions the Chrome Line will last longer. However shoots lots of full-auto or fast semi-auto shooting so you heat the barrel up and you can end up with a significantly shorter lifespan than a cheap Wilson barrel that is shot slowly with SAMMI ammo.
Link Posted: 6/6/2003 5:21:20 AM EDT
I had an 11" and a 20" that both died at about 12,000 rounds. They were shooting 1" - 2" groups at 10,000 rounds, but by the time they had 14,000 on them, they were keyholing the bullets. I was shooting full auto, so I am not exactly sure where exactly between 10k and 14k that they went south. Both were unchromed, steel.
Link Posted: 6/6/2003 5:58:00 AM EDT
Barrel life is dependent on a number of factors, including the type of cartridge being used (high pressure cartridges erode the throat areas faster) and the number of rounds fired. Some studies suggest that fast twist barrels wear faster than slow twist barrels...but the evidence is not entirely conclusive. The same holds true for the argument that stainless 416R barrels last longer than chrome-moly; most "experts" say that's the case but others disagree. The real reason most target barrels are stainless is because they are easier to machine. Full auto rifle-caliber guns would normally erode an unlined barrel faster (because of the high heat generated during full auto fire). However, the chrome or stellite lining of military weapons helps prolong barrel life in machine guns. Supposedly chrome-lined barrels are less accurate than unlined barrels, primarily because of the difficulty of applying chrome uniformly throughout the length of the bore. However, I have seen plenty of shooters win High Power matches using standard Colt HBAR chrome-lined barrels. The new FN sniper rifles are built using Winchester Model 70 actions and carry barrels that are chrome-lined. In fact, they are from the same production facility that manufactures the M240 7.62mm machine gun barrels. Supposedly they are very accurate guns. Serious competitive shooters tend to replace their barrels every 4000-5000 rounds, although guys/gals firing hot cartridges (e.g. 6.5/.284) swap their barrels after about 1200 rounds. The reason isn't that bullets are keyholing, but that they've simply started to "lose their edge" and groups are starting to widen. Many competitive shooters use their "burned out" competitive barrels on hunting rifles--- where they remain perfectly adequate. Of course, your mileage may vary.
Link Posted: 6/6/2003 6:06:32 AM EDT
The 'useful' life of your barrel ends when accuracy drops below your acceptable limit. As everyone says above many factors influence when this drop occurs. ----------------------------------------------- Shoot1K, conventional wisdom is on your side re the accuracy of chrome-lined barrels but I'm starting to see reports of MOA (and sub MOA) from rifles with chrome lined barrels. I don't know if the process has improved or______________ but too many reports to ignore?????
Link Posted: 6/6/2003 6:20:34 AM EDT
[size=6]YOU CAN'T HANDLE THE TRUTH!!![/size=6]
Link Posted: 6/6/2003 7:17:20 AM EDT
Just to add another twist to this discussion, the M1 garand boys use Throat Erosion gages (TE) and Muzzle Erosion Gages. They grade useful life by these readings. I would assume that similar gages would be available for 5.56 as well. I picked up a M1 from the CMP and used the gage while I was at the CMP north store at Camp Perry earlier this spring, and was very amazed at the wide range of readings on different rifles. These rifles vary from well used to rebuilt with new, albeit 50 year old barrels. The cmp says that a barrle with a reading TE reading of "5" will need to be replaced after a few thousand rds.
Link Posted: 6/6/2003 7:41:04 AM EDT
In the military we've got rifles that are only used for qualifying at the range, 60 rounds of relitively slow semi-fire at targets at varying ranges and then 15 rounds full auto at center mass at 25 meters. My buddy is an instructor there. The guns were all made in '87 and they run a serial a week roughly. The guns also have ham handed recruits and retards cleaning them with the three piece issue steel cleaning rods EVERY time before AND after the shoot. On average there would be between 40- 50K through them, 10- 12K being full auto, and being cleaned about 14- 16K times with issue stuff, and not exactly lovingly either. I intentionally looked knowing the # of rnds and abuse, and there isn't any difference in the rifling I can detect with my issue Mark 1 eyeball between that rifle and my brand new preban config. bushie. I still got 2-3 inch groups at 100 meters with it. I think they are so well preserved because a lot of firing is semi and slow, and it's not too hot here most of the year (contributing to keeping cooler bbls.) and a low percentage of full auto is used. Since our ARs probably on a whole are babied more, cleaned more carefully and not used that much on average, we can expect ours to go at LEAST as many rounds if not more. My great grandson'll be the one to wear it out, not me likely. Oh, and the bolts are handed out indiscriminately when you line up, they're not numbered to the induvidual rifle! (guess I didn't really need those headspace gauges!) P.S., I'm talking about C-7's, which are basically an M-16A2 with the old A1 carry handle and sights. Hope those figures shed some light. _______________________________________________ Even my wife has an AR [X]
Link Posted: 6/6/2003 7:46:56 AM EDT
Originally Posted By echap: Just to add another twist to this discussion, the M1 garand boys use Throat Erosion gages (TE) and Muzzle Erosion Gages. They grade useful life by these readings. I would assume that similar gages would be available for 5.56 as well.
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There is a throat erosion gage for the M16 as well. Tought to find though.
Link Posted: 6/6/2003 9:36:42 AM EDT
I don't know the answer, HOWEVER, I've never worn an AR/M-16 barrel out. They always out shoot me! I was issued a well used M-16E1 in VN. I zeroed the rilfe within the first hour I was in my Bn. I shot the rifle almost every day for 13 months. The most I ever shot thru it at one time was in the excess of 1000 rds. Most of the shooting was semi-auto and when I left country, the rifle had not changed zero and it would put 5 shots in a .30 size group at 25 yds. My match AR will still out shoot me after 5K rounds and it is me, not the rifle that keeps me from my Master rating!
Link Posted: 6/6/2003 11:52:22 PM EDT
There is a review of the AR15 A-2 HBAR Colt at Galleryofguns.com. The guy shoots 10,000 rounds of PMC 55 gr in 2 1/2 days with cleanings about every thousand rounds. The review says that at some point close to the end the rounds started keyholing and they found an eroded chamber throat. It's kind of a neat review....just thought I'd mention it.
Link Posted: 6/7/2003 12:18:40 AM EDT
Basically after reading this thread I really did not learn much of anything.
Link Posted: 6/7/2003 12:43:08 AM EDT
There is no carved in stone rule for barrel life. Chrome lasts longer, but how the weapon is used will make more of a difference in how long it lasts. I know people want a "number", but it isn't going to happen with any degree of honesty.
Link Posted: 6/7/2003 1:14:19 AM EDT
Tell you what. Send me a hundred thousand rounds of Q3131a and I'll shoot the bejesus out of a chrome lined Colt barrel and an unlined Oly barrel. I'll report my findings sometime in the near future.
Link Posted: 6/7/2003 9:01:41 AM EDT
I emptied three crates of about 20,000 in each one and only after I started the fourth did it get really bad(about 6" groups from benchrest) even then, I did not get rid of it, I use it for plinking now, at it is still ok for that. I don't remember what type of barrel it was, but it was probably some chromed one from either Colt or DMPS.
Link Posted: 6/14/2003 9:20:50 PM EDT
[Last Edit: 6/14/2003 9:24:03 PM EDT by sfcret]
you can't put a x amount of rounds on barrel life.....it just ain't going to happen. the only way to check the barrel for servicability is by gauges....the military does not keep a tally on how many rounds are fired from this M16 or that M16 (they do keep a record of round fired for weapon systems, but not small arms). as for chrome lined vs un-chromed....that really is a moot point, chrome lining is used to insure the barrel doesn't rust up, or in neglected cleaning....I doubt very seriously that it will extend the life of a barrel more then a un-chromed one. if you are comparing barrel life of a M16 to a AR....your comparing apples to oranges. most manufatuers are not going to spend the extra money putting M16 barrels on civilian AR. no matter what you hear or read about "mil-spec" this, or "mil-spec" that about ARs... there is no such thing, it's more sales hype then fact.....but some folks just have to believe that their ARs are just like M16 only semi, which is just wishful thinking......and they like saying "mil-spec".
Link Posted: 6/16/2003 8:30:53 AM EDT
Everything I've ever read or seen on chrome barrels says that chrome-lined barrels will last longer than unlined barrels, in the same conditions. Corrosion resistance is better as well. As far as "M16" barrels on civilian ARs, Colt and Bushmaster both use the 4150 steel that is specified in the mil spec, and all BM (and some Colt) are fully chrome lined, as specified in the mil spec. So all BM and some Colt barrels are exactly equivalent to M16 barrels (except for external profile). The other manufacturers use the cheaper 4140 steel. Some, like Armalite, chrome-line them like the mils-spec, but most don't. I don't think they claim to be mil-spec though.
Link Posted: 6/17/2003 6:02:47 AM EDT
IN a test, I forget what website it was, the new colt's barrel burned up in 10,000 rounds actually a little before, if you want i can find the website.
Link Posted: 6/17/2003 7:09:08 AM EDT
Originally Posted By dragthewaters: IN a test, I forget what website it was, the new colt's barrel burned up in 10,000 rounds actually a little before, if you want i can find the website.
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Shooting times ran that test about 3 years ago. They shot the 10,000 in 3 days, at times they had to dunk the barrel in water to cool it. They reported no parts breakages. I think that speaks volumes for the quality.
Link Posted: 6/17/2003 12:35:03 PM EDT
chromium is the hardest of the transition metals....
Link Posted: 6/17/2003 6:24:21 PM EDT
Shoot it however you want to and then clean it properly. The shame is in neglecting a tool, not wearing it out. When the accuracy drops below your personal standards replace it. We are only talking a couple hundred bucks for a first rate barrel! The beauty of the AR is that you will never have to make the "do I fix it or junk it" decision that is common with lots of things these days. I am actually proud of myself when I wear something out. It means that I am using it. If I ever wear one of my AR barrels out, I will proudly order the very highest quality replacement for it that very same day, and I just might mount the worn-out one and hang it on the wall. DILBERT_556
Link Posted: 6/17/2003 7:23:56 PM EDT
Dilbert, that is a good way to think about it. That is kind of how I think about shooting as a hobby, sure it is expensive, but I can't take it with me and it makes me happy. Now if you burn out a barrel doing mag dumps, well, it is your money, and you surely have more than I.
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