RE: New 12-Bore jaeger Rifle
A 140 grain load of FF should put you really close to the 1350 mark.
What is your bore size, a true 12 ga. is .729, that .735 must take a stiff wrap to start...........or is your bore bigger?
I shoot .725 to .705s out of my 73 cal, but it only has a 26" long tube. The 725s weigh in the 550 grain area.