Wylde Chamber is normally what John uses, though he has a few others and may use them depending... I believe the 12 twists is a still different chamber, but don't recall what it is.
The Wylde is about as good as it gets as a generic chamber.
Barrels on guns unless mentioned are Wilson tubes but not finished and chambered by them which is where a big difference comes into play.
7 twist. I shot it for years. Liked it more than the 7.7s.... but never shot lighther than 52s. I currently run 6.5 twist barrels so they'll stabilize 90s, but can easily shoot 52s, though it will torch 60 sierra flat base HPs... thin jackets and all and would torch 64 bergers till they put tougher jackets on.
As long as you arent ever going to shoot over 55s the 12 is fine. But that limits you on wind drift a lot. 7 twist will work just fine down to the 52bthps... and still allow you to shoot without a doubt, the 69s and 73/75s if needed for longer shots in the winds.... About all I shoot coyotes with is 75bthps... works just fine. At least out to a couple hundred yards, never shot one past that so far. Although there was the time we shot at one around a mile away and got so close... but that was with a 300.....
Jeff
