Coils I agree with the plug - I would thread the plug and not simply weld something in. That way the threads help seize the plug in place. I really don't think it would blow out with the smaller calibers. We always tell people that drilled into the chamber to just get a new barrel because they are available... if barrels aren't available, then the plug is the only way to go. I would be interested to find out what shear forces threads can take. I know on an engine block when you torque down the threads on the header bolts, the only thing holding the pressures IN is the bolts, so a threaded bolt must be able to handle some pretty good pressures. What pressure is that called? Torque to Yield or something like that? Surely we can find that info to calculate safety margins for a plugged chamber.
Barrel journal is 1.179 on mine. The locking tab that the carry handle presses against is 1.4" but a slip-on collar could be employed to make that little piece. I think that piece is there only to keep the carry hanlde in place anyway.
The problem with a PK is that you will need to set the headspace when you make the barrel. The slot for locking tab (that attaches to the trunion) is machined onto the barrel so you will need to set headspace and cut that notch.