Doble:
Thanks for the information. I might look into doing the lathe bed extension if my wife will let me back in to the garage any time soon! It looks like a big project, so I'd better save up my brownie points.
DJ:
By "arbor" I assume you mean the mandrel for facing off the receiver. I did it, but it was a tough for my first project.
As I recall, I cut a 1" cold rolled steel bar off to about 10 inches or so, which is about the bare minimum that would work with the length of the receiver. I chucked one end of the bar in a four-jaw chuck, set up a steady rest, dialed it in, and center drilled the far end. I then used a dead center in the tailstock and turned down the far end to about .700. Then I reversed the process and turned down the other end, leaving around .600 in length about 2/3rds of the way down the mandrel at the major diameter of the small ring threads. Finally, I threaded this area to screw in to the receiver. It looks like the Brownells receiver facing mandrel, just shorter.
I'm sure this would have been much easier and more accurate on a larger lathe, but all I had available was the mini-lathe. The mandel seems to work ok, however, since I am able to get about 1" groups from the rifle I built (using the original Turk barrel cut down to 24" and crowned on the lathe).
My next step is to build one for a large ring receiver. The only downside is that it takes a long time to reduce the diameter of the mandrel down to .700 or so on one of these small lathes.
Hope that helps,
AE