Bramble- Excellent description once again. Yes that was the logic I used for a 1:22 twist. I also found it worked on a .700 I built on a regular .50BMG rimless case. Progenitor of the 12GaFH!
I was just doing some measurements on my Zabala 10Ga( BTW it is a 3.5 inch magnum) barrels in order to supply pac-NOR with some specs. Looks like at the rear end of the monoblocks the barrels measure 2.323 across with some room to spare. I need to keep the muzzel wall thickness as large as possible for the 12gaFH because of its muzzel pressure, so do you think a barrel of 1.16 for 3"( the barrel will be turned down to make the tenon and threaded to go into the monoblock, but will be 1.16 at the rear end of the monoblock, followed by a taper to 1.1 in 3 inches, then straight 1.1 for 18 inches at the muzzel will fit and look OK? Or do I need to account for the taper of the chamber section of the monoblock? Again, Thank you very much for the information, nothing like experience to save making mistakes.-Rob