The 1911 Barrel Bushing

Discussion in 'Gunsmithing' started by pokute, Oct 21, 2014.

  1. pokute

    pokute Sincere as a $5 funeral

    Thought I would share some thoughts on the 1911 barrel bushing. The bushing is a critical part to the cycling and accuracy of the 1911. It's usually the first thing you replace when accurizing a 1911.

    The lockup of the 1911 is sometimes referred to as a "3-point lockup". In the ideal case, at full lockup, the barrel is held rigidly between the bushing, the frame, and the slide.

    I'm going to take a chance of being called a fool here by saying that the only part of the lockup that I fully understand is the barrel-to-bushing.

    First of all, the O.D. of the bushing should fit the slide opening snugly. You should just barely be able to turn it by hand.

    At full lockup, the barrel slopes slightly downward from back to front, and should fit the bushing with about 0.001 clearance at the upper rear and lower front. And just enough clearance otherwise so that the bushing can still be turned at link-down.

    At the same time, at full lockup, everything at the breech end is supposed to be adjusted so that the barrel can't shift or rotate, without the barrel springing at all.

    At this point you can probably see why a bushing style compensator will probably degrade accuracy. But I digress...

    The breech end is described as being fitted at the rear and sides of the hood, the link, the lower lug, the upper lugs, the vertical impact surface, and the barrel bed of the frame. The truth seems to be that it is fitted at as many of these places as is convenient, without interfering with the function of the pistol. See Kuhnhausen for the gory details.

    Notice that your barrel (except on a GI pistol) is turned down to a smaller diameter a little way back from the front. That is to facilitate clearance of the bushing as the barrel links up and down. It improves reliability without affecting accuracy.

    A GI pistol usually stands on the link, has an unfitted hood, and unfitted lugs (top and bottom), it usually has generous bushing clearance to avoid binding. A GI pistol with fitted bushing and a Dwyer Group Gripper has a whole different lockup. So, there's at least three different full lock-up states - Ideal, GI, and Dwyer. With a lot of possible variations on ideal.

    If you find yourself having to deal with a pistol that doesn't lock up properly, you can have anything from an easy time to living hell getting it fixed!

    Fortunately, recent SA 1911's seem to be coming out with some version of ideal that SA can replicate ad-infinitum. So most folks will never have to deal with lockup issues at all. As always, lemons ARE possible, but SA will make good on those.

    You may consider fitting a bushing yourself just to appreciate what goes into it. I'd recommend an EGW thick-flange bushing for this project. Order it directly from EGW, and give them your slide I.D. and barrel O.D. (at the front end of the barrel) to avoid getting into the hellish mess you will get if you order it from Brownell's and get a random-sized one (Brownell's pretends that bushings are a one-size-fits-all proposition - This can result in a one hour job taking a week or more - guess how I know). Any fitting that needs to be done can be accomplished by wrapping some SiC paper around your index finger and going at it. You can shape the outer edge of the EGW bushing flange to a really smooth radius with a file and some silicon carbide paper, it will look really nice.
    Last edited: Oct 21, 2014
  2. pokute

    pokute Sincere as a $5 funeral

    Just realized I failed to explain the difference between straight-bored and angle-bored bushings.

    A straight-bored bushing must be relieved at the upper rear and lower front of the forward ring to accommodate the lockup angle.

    An agle-bored bushing (sold by EGW) or a bushing with a floating ring (Briley) are relieved by design, as sold. They significantly reduces the amount of work that is required to obtain a close fit. The ring in the Briley bushing is very hard, and cannot be fitted at all. It must be ordered with the correct i.d. I'm not convinced that the Briley is better under any circumstances than the less expensive (and more adaptable) EGW angle-bored.