I don't have any figures for you but when changing out parts on my new blued Series 80 Colt government model, one of them was a stainless match barrel bushing from Wilson. It fit the Colt barrel very well without any slop and helped my accuracy right off. After some firing at the range I would take it apart to look and it looked like it broke in with the barrel real well. No wiggle at all and a very slick and smooth slide up and down the barrel. Might have just been lucky. I did have to have a smith fit my slide stop but the rest of the stuff I put in.
When I fit match grade bushings, (they start out so tight the bushing won't even go on the barrel), I like to get the very tightest fit I can and still be able to slide the bushing on the barrel with minimal friction.
Equally important is the bushing-to-slide fit. It needs to be tight enough where it takes a bushing wrench to turn it.
These two fits have a considerable affect on accuracy. Of course, these snug fits are for target guns. I would recommend a standard bushing for a carry gun.
I just completed a bushing replacement on my AMT Hardballer II. I followed the instructions in Kuhnhausen's book "Colt .45 Automatic: A Shop Manual". There are enough differing considerations, you really should have the book to guide you through all the fit-up points. Not only do you have barrel to bushing and bushing to slide fit, but there are points on the bushing that may need to be relieved to allow the barrel to tilt downward as the slide cycles. These same points may need additional attention to prevent barrel springing.
This sounds more complicated than it actually was to accomplish, but that is because (I believe) Kuhnhausen's book assumes the worst case & provides guidance for each potential problem.
For me, this was hand-work, no machining was required. Though the book does provide info if you have a lathe available. Part of my success I believe, was miking the barrel and slide first, prior to ordering the bushing. Brownell's catalog is a big help in that each after-market bushing is listed with a nominal OD & ID. This will help you select the bushing requiring the least metal removal.
I just purchased a new national match barrel bushing that fits the barrel snug but needs fitting to the slide. I think the accuracy problems can be a bunch of problems that when added up all together can be poor accuracy but i think from what i'm seeing the worst fit is in the barrel bushing to the slide. My orginal bushing is very loose in the slide.
I just buffed my slide where the barrel bushing goes into it and i fitted the national match bushing snug. You can just turn it into place with the bushing wrench and its snug with zero clearance. At first the old one had more slop in any direction it was that loose. I reblued everything before assembly. Its funny i have checked a few newer 45's here and most of them have very loose barrel bushings in the slides. The barrel bore in the new mational match bushing seems to be perfect its just right. I think the old 45 i have will surely punch some nice groups now.
Another to reply without directly answering your question....
I have installed four EGW Angle Bored bushings now: 1-Govt 45, 2 - Cmdr 45, and 1- Govt 38super. All require a barrel bushing to remove the new bushing from the slide. Without measuring, I'd say I have about 2-thousands clearance between the barrel and bushing. I used the same methods as described by the others. I worked the bushing's ID until the barrel would just fit in. The "angle bore" from EGW takes care of the vertical clearance for the barrel to lock-n-unlock during cycling.
Accuracy in all pistols improved by a 30-50% margin. I'm very pleased with the time and elbow grease spent to install these bushings.
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