Funny that you bring that up Mike.
I still haven't done a chamber cast as of yet but I did make some interesting discoveries - including how bad my original measurements were.
The groove dimensions are actually .453 and the base is still .536.
Length was off though. The chamber will eat a 45-70 case. I tried fitting a reformado in it but not enough taper above the base.
Looking forward to that cast.

Tom

Carbonation without fermentation is tyranny