My first barrel fitting project is to fit an A1 type barrel to a Springfield 1911A1 slide and frame (Mil Spec model). I wanted a steel (not stainless) barrel and decent quality, so I chose to use a Kart barrel for the project. The Kart barrels have National Match dimensions, with a reduced barrel diameter beginning 0.375" back from the muzzle and extending back to the chamber. I wanted a uniform diameter barrel though, not NM spec. So I needed to take about 0.005" off the diameter at the muzzle end, to make the whole length uniform. This would leave me with a barrel that was only 0.003" under spec at the muzzle, and only 0.001" under spec for the remainder of the length (A1 spec).
Not having a barrel mandrel, I needed to make one. I used a 1/4" schedule 40 brass nipple, cutting off the threaded ends to get them out of the way. Also, not having a 4 jaw chuck, only a 3 jaw scroll, I turned the mandrel to fit the chamber end of the barrel and left the mandrel in place in the chuck. I added a 10-32 brass screw to act as a dog against the side of the barrel hood.
The muzzle end was supported by a live center at the tail stock. I took off 0.0005" at a pass, until it was 0.0005 over finish dimension. A stone and 2 grades of fine sandpaper then finished it. The barrel is now a uniform 0.575" along it's length. If there is any step left in the transition between the two original diameters, it is invisible, and imperceptible to the touch.
This was all done on a mini lathe. These small lathes have some serious limitations, but as long as you work within those limits, you can do some serious work.
My next mandrel will be for the barrel bushing and will use 3/8" brass pipe.
Brass pipe is readily available in many sizes, and being pipe, not solid, it is lower cost than solid rod and easier to cut to length.
-
Bookmarks