I am working on fitting my first Kart NM barrel. I have the hood sized at this point and I am now ready to move to the lugs. I have heard conflicting information about which lug to file. I have heard some say that you should file the slide lug and some say you should file the barrel lug. Which should I file? It is the rear most barrel lug that is over sized, correct?
Did you get any instructions with the barrel?
Reason I asked is because the usual sequence of fitting a NM barrel is to first equalize (fit) the barrel lugs to the slide and then trim the hood so the barrel fits into the slide.
In any event, which barrel lug (or lugs) needs work depends on the slide. Read through this from our Stickies section: http://forum.m1911.org/showthread.php?t=25473
There were no instructions with the barrel. Have I wrecked it? Thanks for the point in the right direction.
I don't think you've wrecked it - it's just that any fitting of the barrel lugs to the slide lugs will increase the difference between the gun's static & dynamic headspace. For lack of a better term, I call that difference "endshake" - and it's how much fore-aft play exists between the barrel & slide when the barrel is all the way up into the slide in battery.
How much endshake do you currently have?
How many lugs currently make contact?
How much dynamic headspace do you currently have?
You're ok, fit the hood to the slide, all the while going slow as the lugs start engaging. Don't worry about the lower lugs yet. Get the barrel aligned in he slide, so the primer/flash hole lines up.
The last thing you do is cut the lower lugs.
There's an article on Blindhogg about fitting the Kart barrel, so this may help ya out.
http://www.blindhogg.com/gunsmith/barrel.html
Quote:
I have heard conflicting information about which lug to file. I have heard
some say that you should file the slide lug and some say you should file the
barrel lug. Which should I file? It is the rear most barrel lug that is over
sized, correct?
Before doing any filing, you should make use of a black felt marker, your calipers and maybe some modeling clay to see if the barrel lugs actually line up with the slide recesses. There is no guarantee that the parts will automatically have perfect alignment. Concentrate on the front faces of the barrel lugs. While it is possible to fit the barrel with just the #1 lug bearing, it is always a good idea to try for at least 2 lugs bearing. Take measurements, sketch it out and see how things line up.
I find that most people will never be able to take advantage of the quality of barrels that are out there. As long as the barrel is of good quality, fitting will be the deciding factor.
A little off topic but here is a x-ray photo clearly showing barrel lug engagement just before a round leaves the barrel:
I would alter the barrel before the slide because the slide is more difficult/expensive to replace.
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What is the best tool for machining the outside of a barrel bushing?
Larry Vickers taught me to use a belt sander.
Brownells has a slick tool to chuck the bushing into a drill press. You then use abrasive strips of your choice in a "shoe shine" fashion.
Here is a posting from Log man that shows how to make a tool for this:
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A simple to assemble fixture to spin your bushing to reduce the OD can be
had by a trip to the hardware store and now you can use file, stones or paper
and reduce it until you get the fit you wish. 3/8" flat head, nut and
washer.
It is a good idea to make yourself a sloppy fit bushing - one that holds the barrel loosely - during lug fitting. You do not want to install a tight bushing until all the lug fitting has been done. Note that in the x-ray view (above post) it appears that the front faces of all 3 upper lugs are bearing. That is the ideal, and that's why you need your felt marker and measuring tools.
FWIW, here's the pic Eric posted after being given a double dose of sharpening:
