November 04, 2013
Recently, I was test-firing a Chinese Norinco 1911 imported into this country in the early 1990s before the Clinton Administration shut off Chinese imports. The Norincos were a faithful mechanical copy of the 1960s Colts, but fit and finish left a bit to be desired.
This particular pistol functioned 100 percent and combat accuracy was good. Examining it later on the bench revealed poor lockup between the barrel and slide lugs, and some minor peening or "flanging" of the lugs was evident.
Engagement was an unacceptable 50 percent or less. The bottom lugs of the barrel had been cut a bit too high. For occasional use, this pistol could serve for years before a real problem developed but at that point the slide might be ruined.
The only good fix for poor lockup is a new gunsmith fit barrel. But before we can fit the barrel we need to dress and polish the slight ridge at the front of the slide lugs. No problem, you think. We'll use a sanding drum on our Dremel Flex-Shaft attachment to polish these surfaces.
Not so fast, grasshopper. Minimum depth of the slide locking grooves should never be less than .055 inches, and the Norinco slide measures .058-.060 inches. A sanding drum could reduce the lug height below minimum in a matter of seconds. I've seen slides ruined with power tools.
Polishing by hand is slower but has a higher chance of success. Brownells markets a special tool known as a "lug iron" for careful dressing of the slide lugs. A piece of abrasive cloth — 320-grit is recommended and seems to work well for me — is clamped on the drum shaped end of the tool and inserted into the slide.
Keep the tool parallel to the slide bore and replace the paper as needed. Monitor the lug height to be sure it is not reduced below the .055-inch minimum. Removal of a couple thousandths is all that is usually needed. Once the burr or ridge is gone, stop polishing. The lugs should be smooth and square, ready for a new barrel.
Brownells Lug Iron
The Brownells lug iron and a strip of 1-inch wide 320-grit abrasive cloth are just what you need to break burrs in the slide lug area. Don't use your Dremel tool for this job.
If you look closely at the area of the lugs indicated by the arrow, you can see a raised edge known as "flanging" caused by poor lockup. This will lead to poor accuracy.
The clamping bar secures the ends of a 1-by-2-inch piece of abrasive cloth on the lug iron. Keep the tool parallel to the slide bore while polishing and replace paper as necessary.