After I got one from each of the 4 makers, I started with the idea of a SA in each number range - 1m, 2m, etc. Seemed like a good idea at the time, but restoring these was getting pretty expensive.

Then, I found I just couldn't pass up a plugged receiver/'52 barrel combo. I was going to pull the plugs and mount an M1C bracket on it, but I think I'll save up and leave this SA-52 rifle as a example of a plugged receiver in the collection and save up for a good M1C.