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Thread: anybody fire-lap their barrels??

  1. #11
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    I have seen the results of some informal testing... but it is pretty much what you would suspect.

    An *accurate* barrel should be lapped, most are lapped by hand and the benefit is obvious... fire lapping does what it claims, but it also seems to be rough on the throat of the chamber, wearing the throat as it laps the barrel.

    The only case I have heard of, and again this was what I was told, is that barrels that are fire lapped, then set back are indeed very, very accurate barrels -- but setting back an AR barrel is pretty much out of the question.
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  2. #12
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    Quote Originally Posted by K.L. Davis View Post
    I have seen the results of some informal testing... but it is pretty much what you would suspect.

    An *accurate* barrel should be lapped, most are lapped by hand and the benefit is obvious... fire lapping does what it claims, but it also seems to be rough on the throat of the chamber, wearing the throat as it laps the barrel.

    The only case I have heard of, and again this was what I was told, is that barrels that are fire lapped, then set back are indeed very, very accurate barrels -- but setting back an AR barrel is pretty much out of the question.
    Ken, do you have any data on the amount of wear induced by firelapping? Tubb's Final Finish has 50 rounds, five groups of ten with progressively finer grits.

    He mentions if starting with an already "decent" barrel, skip the first two coarser grits and just use the finer last three. Any idea how much leade is worn off when using in this manner? How much leade is worn off after shooting 1,000 rounds in a normal fashion?

  3. #13
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    McMillan said the only way for a non-professional gun owner to lap was with a lead lap. It's in the link.

  4. #14
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    LittleLebowski,

    I'm not seeing it.

    I see:

    (1) Don't buy into the break-in stuff that advises to fire a shot, then clean,

    (2) Don't use JB, and

    (3) All of this is moot if you are discussing chrome-lined bores, since all the advise he doles out is WRT unlined barrels.

  5. #15
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    Quote Originally Posted by jmart View Post
    LittleLebowski,

    I'm not seeing it.
    Right there in the link I posted:

    I wouldn't be as apposed to it if it were applied on a lead lap and very sparingly.

  6. #16
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    I guess I just read it differently. Seems to me he's comparing when it's appropriate to use JB, and he's critical of it's use on a patch for the reasons cited in the link. Then he goes on say that it wouldn't be as bad if were applied sparingly on a lead lap. But he makes no mention of pros/cons of firelapping.

    One point he does make is that when lapping compound is applied using a lead lap, one of the cons is the comparatively greater affect occurs at the end of each stroke where the lap's direction is changed, i.e., more lapping occurs in the throat and muzzle compared to mid-bore.

    One of the benefits Tubbs cites with fire lapping is that this effect doesn't occur since the lapping/burnishing is effect is all going the same way as the bullet travels down the bore -- tool marks are burnished in the same direction as the bullet's travel and no excessive lapping occurs at the ends.

    Again, no real idea what the effects of fire lapping are on a chrome-lined bore. I don't know if the chrome is so hard that it has no effect, or if it actually makes the bore more uniform and takes care of uneven chrome application.

  7. #17
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    I see your point. I just don't see the point of trying to lap chrome lined barrels or any others for that matter. Seems to me a good cleaning would work just as well at "restoring" a bad barrel. I don't see how anyone can argue McMillan's point that the lapping will wear down everything equally including wearing down the copper first then the steel, not just the copper and that will lead to uneven spots in the barrel.

    There's any number of adherents to each school of thought but I see more and more people saying "just shoot it and clean when accuracy breaks off."

    Here is a great thread started by a Marine Scout Sniper School instructor on the topic.

  8. #18
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    Quote Originally Posted by bullseye View Post
    i say to each their own, i've been doing what i do for too long now to change, [i hate change anyway, doesn't everyone].
    Yeah, but I hate missing targets worse. I have been known to change my ways in order to be more accurate.

    i've been with the sinclair inter. crowd too long to jump ship now, due to some internet chatter.
    I'm a little puzzled when people post assertions without evidence to back them up, then when somebody is reluctant to agree due to simple lack of evidence, suddenly the internet is just chatter.

    no one is gonna convince me that a fouled barrel will shot as well as a clean one, ... smooth them suckers out, they'll shoot better longer.
    How fouled are we talking about? Have you done any tests to show how much and how fast your groups open up with more fouling? That's all I'm asking.

    krieger also cryo's and hand-laps their barrels before sending them out.
    Didn't see a mention of cryo on their page about barrel making, http://www.kriegerbarrels.com/Barrel...246-wp3379.htm , and I doubt a regular barrel could be made to approach a Krieger just by lapping.

    Not trying to bust your chops, it's just that I've seen a few theories and myths come and go as to what causes accuracy or lack of it.
    When life gives you lemons, insert copper and zinc wires in them and repeatedly shock your tongue.

  9. #19
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    this has turned into a very interesting thread [for me], some real good points made. i had never the one about ""the rough throat shears copper then vaporizes it", sounds very plausible to me. i do personally think david tubb overdoes it though i don/t use 220 grit, shoot 3 400, clean,,5 800's, clean- 5-10 1200's, clean and i'm through. slick as the proverbial whistle. i'm not concerned about what little leade i lose in an ar-15, as i seat to mag length anyway, no bullet comparetors inolved. thanks for all the good info guys, good shooting.

  10. #20
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    Fire Lapping has its merits


    As a former Benchrest Shooter it is my opinion that firelapping has its merits and is used by some Benchrester Shooters although it seems to have fallen out of favor over the last few years.

    I don't believe that it would really benefit the average AR Builder using combat grade Bbls. Unless you are trying to build an AR capable of consistent sub MOA groups consistent then the process is more trouble than it is actually worth. Keeping in mind that while we may put thousands of rounds through our Bbls, the life expectancy of a competitive Benchrest bore is only around 2000 to 2500 rounds.

    I have heard of some shooters who have Fire Lapped a Barrel trying to rid it of the (Alligator Hide Effect) which appears in a barrell having many rounds ran through it, or to loosen up an obviously tight bore.

    I have always used the one shot clean method to break in a new barrel with good results. I have a Remington 700VS rechambered to .22-250 Ackley Improved that shoots in the 3's consistently, with a best group of five going into .248". My old 700 BDL Varminter is .223 Rem shoots almost as well, and both will hold minute of crow out past 300 yards.

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