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Barrel expected degradation due to usage (Page 2 of 2)
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Originally Posted By bpm990d: How are you shooting, that you perceive a .25/.50 moa change? Competitors shooting service rifle usually ditch their barrels after about 3K rounds, because they start to throw fliers at 600 yards. That being said, how it's used and cleaned can have an impact on how long it will last. I don't think I've ever worn out a barrel, but I have a stack of them that I don't trust any more. Here's a general planning rule for highpower rifle competitors. It may or may not apply to your shooting style. The highpower course of fire covers slow fire (one shot per minute) standing -- either ten shots or 22 shots depending on the type of match, typically with 69 through 77-grain bullets. The second stage is ten-shots rapid-fire in 60 seconds (two shots and a magazine change of 8), or two sighters in two minutes followed by two ten-shot groups. You repeat the rapid-fire stage at 300 yards. This is where barrel wear starts to become obvious -- are your groups (checked against previous performance recorded in our data books) growing larger? Are your scores dropping ever-so-slightly? Are your groups clumping together into two or more clusters? At 500 or 600 yards you'll shoot 10, 20, or 22 shots with one minute per shot. Here's where you'll notice -- are your shots going off-call ("Man, that broke as a 10 at 3 o'clock but that's an 8 in a direction completely different than I held or called")? When you start getting one or more like that per 20-shot string it's time to throw that barrel away. Can you still shoot bullets from it? Sure, the gun will go bang and it will launch a projo through space -- but it may not land where you're aiming at 300 and 600 yards. You can generally predict your rifle's throat will advance .001" per thousand rounds. All barrels will wear (including chrome-lined) by going smooth (maybe 1/8 to 1/4 inch), then fire-cracking as the powder burning temperatures at the case mouth affect trace alloy molecules and temperature cycles cause the steel to get that alligator-scale and dried cracked mud appearance you see in borescope pictures. Competitive shooters may go 3000 to maybe 5000 rounds depending on their skill and score expectations. This is the third group from a brand-new Criterion barrel at 200 yards, resting on top a sandbag (no glove, sling, or shooting coat), shot with a 4.5x scope: Attached File |
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Everyone has their own way of cleaning a copper fouled barrel. I have a Remington 700 that gets dirty and copper fouled after just 30 or 40 shots. It get's cleaned often. I use a bronze brush first to get out as much carbon as possible. Then I use Hoppe's on a patch to get the easy stuff the bronze brush does not get. After the Hoppes I use some Brasso that has been fortified with Patch Out (both are ammonia based) and scrub the barrel and let it set in the barrel for 30 minutes at a time for any copper or carbon that is left. I might have to do this twice. Since I have a bore scope, I look down the barrel with it and then I know if I need to do it the second time. To get the Brasso out I use some more Hoppes or I use some spray carburetor cleaner to spray down into the barrel. Don't use the spray carburetor cleaner if you have a finished wood stock. The carb cleaner will strip off the finish. Keep in mind, if you use a bronze brush in combination with the Hoppes, Brasso or Patch Out, it will eat away the bronze brush. My favorite plastic brush is an ISSO. |
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Changed the barrel to White Oak Armament 16" SPR, replaced the buffer with the lighter buffer, and installed the Superlative Arms adjustable gas block. After gas block adjustments and zero adjustments, here is how it looks like:  I feel like this barrel wants better fundamentals out of me. |
Barrel expected degradation due to usage (Page 2 of 2)
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