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Posted: 11/4/2010 9:03:18 PM EDT
| I am sure that this has been covered, but I cannot find it anywhere. What is a general guideline for round count/barrell life? I know that it depends on a lot of factors. But what is a general ballpark that you barrel is really crapped out? Like as in it won't hold a, say 4'' group at 50 meters? I have heard that barrels are shot out at 6000 rounds, and I have heard 20,000. What are some real life experiences? Thanks, 9080 |
| Depends on numerous factors––barrel steel quality, method of rifling, pressure of cartridge, frequency of cleaning, rate of fire, chrome lining, lead/jacketed bullets to name a few. Ultimately it boils down to accuracy. It's good for as long as it meets your accuracy expectations. |
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Quoted:
Depends on numerous factors––barrel steel quality, method of rifling, pressure of cartridge, frequency of cleaning, rate of fire, chrome lining, lead/jacketed bullets to name a few. Ultimately it boils down to accuracy. It's good for as long as it meets your accuracy expectations. Agreed. But I have seen some of my own go in excess of 12,000 rounds without accuracy suffering. I'm not a mag dump guy, but will shoot rifles under slow sustained fire until they are really hot. I've had a cheap non chromed barrel go 10,000 rounds. i traded it to a buddy of mine and he has put another 3,000+ through the rifle. Still shoots well. Too many factors involved in this. |
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The book "Death From Above" has some very complete data from the Tarnewitz trials of the FG42. This involves several rifles (six, I think) being fired on a schedule of something like 50 rounds semi auto, 50 rounds full auto, then cool with compressed air, and repeat until destruction. Keep in mind these are mild steel barrels, no lining, being used with steel jacketed 7.92x57mm ammo. Average barrel life was about 12 000 rounds, with the range being from about 7 000 up to almost 20 000.
Obviously the 5.56 round out of a chrome lined barrel will give different numbers, but I thought the Tarnewitz results were very interesting, both for how long the soft barrels lasted under such a brutal schedule, and the wide range of results from identical barrels in an controlled test. |
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The USAMU replaces barrels at the 3000 round mark. Not because they are wore out, but because they are fielding over 100 match rifles and don't want any problems whatsoever. They intend to win the Inter-Service matches and Camp Perry, they want no excuses rifles.
Most match AR rifle builders suggest not even considering a new barrel until you have at least 5000 down the tube. This suggestion applies to top shooters as well as the novice. It includes the men and women trying to win at Camp Perry too. These rifles (both the armed forces and civilian match shooters) have a much higher standard of accuracy than what's expected elsewhere. These rifles must be able to hold a 12" group at 600 yards at a minimum when using iron sights. Six inch groups at 600 yyards is preferred. Virtually any rifle will hold four inch groups at 100 yards with quality ammo no matter how many rounds have gone down the tube. Shooting ball ammo is a different story and even the best rifles might not get a four inch group shooting fmj's, even when new. I say it's time for a new barrel when the cleaning patch gets hung up in the throat. You know you have a rough rifle when the area just forward of the chamber is chewed up, course and grabs at your patches. A lot of rifles shoot well despite having shot rough throats. More than a few rifles will develop a tear at the gas port that rips at the bullet's jacket as it passes. This raises hell downrange. The crown area of a barrel that has seen better days will enlarge because of the repeated firing. It won't be perfectly round anymore either. Sometimes taking one inch off the barrel and recrowning it will work wonders. |
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