Run the 377gr in a 1-9.
In my experience with 6 lots of H50 charge weights varied from 138.5-142.5gr with one caveat, 40" K&P.
A 400 Lazer is your best bullet for the 375 CT in my experience and a 1-8 spin, best results beyond supersonic. Again, this is with a 40" K&P and with 138.5gr H50.
Single stage, 3 pound, yellow/black model 667S with solid, curved trigger, small pin design. Just not to my liking so give one a try at a discount. $130 shipped. No trades please.