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Thread: Clinic-3: BFC

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  1. #111
    Join Date
    1st June 2004
    Location
    Lexington, North Carolina...or
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    Quote Originally Posted by OD*
    Yes you were Johnny, I misread your post originally, my fault.

    The three I know for certain that have way more than 5,000 rounds through them show no signs of deformation, now they do have the polished appearance.
    It may not go much futher thant that. My 91A1 beaters radiused the corners
    fairly early one...at about the 10-12k mark and have remained pretty much the same. One has a little more peening...another a little less. Variables dictate the amount.

    On the ones that really get pounded, it normally doesn't amount to much more than what was shown on the two in the pictures. In other words...Only rarely will it cause a fuctional problem, and usually only in difficulty removing the firing pin stop if the metal gets flanged. Colt Series 80s that take the hit around the plunger can present a problem though. Keep an eye on those.

  2. #112
    Join Date
    1st June 2004
    Location
    Vatican City
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    Colt Series 80s that take the hit around the plunger can present a problem though. Keep an eye on those.
    Good advice sir, thank you.
    "The pistol, learn it well, carry it always ..." - Jeff Cooper

  3. #113
    Join Date
    24th February 2006
    Location
    Michigan
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    93
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    I'm goin' all the way back to the beginning on this one Tuner...

    What kind of pressures are you using when you proof equalize the lugs? +P, +P+, 45 Super? Any of those close?

    What are your preferred barrels for doing the perfect fit job?

  4. #114
    Join Date
    1st June 2004
    Location
    Lexington, North Carolina...or
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    The Beginning

    Quote Originally Posted by Involute
    I'm goin' all the way back to the beginning on this one Tuner...

    What kind of pressures are you using when you proof equalize the lugs? +P, +P+, 45 Super? Any of those close?

    What are your preferred barrels for doing the perfect fit job?
    Howdy Involute.

    First...Understand that in order to fit for lug equalization, you have to have a
    reliable means to measure the distance form breechface to the rear lug face of all three lugs. Otherwise, just buy a Kart Easy-Fit and follow the instructions. Unless the lug locations in your slide are badly out of spec, the KEF system will fit to the #1 lug 95% of the time, and about half the time, you'll pick up one of the others...either right away or within 500-1,000 rounds.

    For the money, it's hard to beat Kart's barrels...Easy-Fit or full fit. Excellent barrels. I haven't been disappointed yet.

    For pressure equalization, there are a few caveats.

    Many years ago, it was pretty much SOP to get #1 bearing the load, nad leave lugs 2 and 3 to within .002-.003 inch of contacting...and equalizing with proof-level ammo. The softer steels allowed that approach with good results. These days, the steels are harder, and require more time to settle back and equalize, and I do NOT recommend it with proof-level ammo unless you've actually fit for equalization, and/or the lugs need less than .002 inch to come into play. Much better to do it more gradually with lower pressures
    than to bust a lug.

    You can speed it along with a handload that I've used in the past, but start
    a full grain below this data and work up to it in 2/10ths increments.
    The seating load is: A 250-grain jacketed bullet and 6.5 grains of Unique.
    You may want to use a hard cast lead bullet for the first 4 or 5 rounds, followed by the jacketed bullet for another 4 or 5. Then just shoot the gun
    with hardball-spec 230...about 500 rounds should be enough, unless your lugs have farther to set back than .002 inch. After firing the heavy rounds, check the barrel lugs for flanging at the top front, and stone it flush with the top surface of the lug. If you see flanging, the lugs are being deformed a little, and that means that they're being set back toward equalization, and if your initial fitting was done correctly, that may be all you need. The lug that's bearing the brunt will have the heavier flange...or if there's only one lug in the game, it'll likely be the only one that gets flanged. If that amount of setback brings one of the others in, that may be all that you see. A note: Heavy bullets seat the lugs faster than light ones...even if the light ones are loaded to +p+ pressures.

    Also, due to the fact that the barrel tilts INTO battery, lugs 2 and 3 may not show evidence of full-depth seating, even though #1 is. Typically, 2 will have a few thousandths less, and #3 a few less than #2.

    Lastly, whatever amount of lug setback occurs, the working headspace will increase by that amount, as will barrel to slide endshake, so fit the hood to breechface with light to medium contact to allow for the seating process.
    After seating and break-in, if that contact is still a little too tight for your tastes, you can take another couple thousandths off the face of the hood to get some "dirt clearance" there. I like about .003 inch for the best compromise between accuracy and reliability.

  5. #115
    Join Date
    29th July 2006
    Location
    Phoenix, AZ
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    Let me just say thanks for the excellent barrel fitting info. Knowing what to shoot for gives me a whole lot more confidence when judging a barrel's fit.

    To round out the discussion (I don't think I missed it...) I'd like to request a few comments on the procedure for dealing with where the firing pin strikes the primer. It is clear that every slide is going to have different dimensions and that upper lug engagement is first on the list of priorities. Kuhnhausen shows a tool that locates the firing pin port dead center with the chamber, but most of us won't be boring our firing pin ports after fitting a barrel! At what point in the barrel fitting process do we assess the position of the f.p. relative to the barrel height and make adjustments if necessary?

    A related question: I noticed that one of my 1911's shows noticeably more black burned powder marks on the outside of the spent brass than the others. The marks are concentrated on one side of the spent brass. Do the powder marks (along the length of the case) by themselves indicate that the the barrel may be linking down too early before the pressure drops? Or perhaps the marks vary depending upon the actual chamber diameter and type of brass used?

    I've studied some of the Schuemann barrels that actually have fluted chambers. They are supposed to cause the cartridge to "self-center" in the chamber by letting some of the high pressure gas flow around the brass. I always wondered about that design, and whether your chamber would get clogged up really quickly.

    Thanks!
    Lazarus
    "Do not fix that which is not broken."
    Last edited by Lazarus; 4th August 2006 at 10:08.


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