Just a minor update on the .45 conversion this weekend. I got the handguard retainer extension turned and soldered on the barrel. Then I milled the notches for the handguard retainer lugs. The top of the notch looks crooked in the picture, but that's just a reflection.
The unmodified 16.5" M1A1 barrel has the taper right where the handguard retainer needs to be. Because of this "inconvenience", I had to turn the taper off and then fabricate a sleeve to extend the portion of the barrel where the retainer goes.
After I soldered the sleeve on, I turned the diameter to fit the retainer. I won't cut the notch for the lock lever until the barrel is actually pinned in the trunnion. Then I can use the lower handguard to set the spacing for a perfect fit.
The next few steps will be to get the receiver finished. I have a couple Robert Ibe 0.050" blanks on the way, so I can get some more work done. Once the blanks arrive, I'll trim the top rails and straighten them out. Then I can cut the blank for the correct length. I'll cut the front of the blank at 1.200" inside height as with a normal build, and then attach the template. After the template is on, I'll cut 0.800" off the front of the receiver to get the proper alignment with my other modified parts. From there, it's a normal build (except for the magwell).
Stay tuned for more updates.