[Austin W Hogan]

Chris ; Each number of parker frame size increases the firing pin separation by 1/16 inch, and the breech width by 1/8 inch. This means that the chamber and first few inches of barrel are nominally 1/16 inch larger in a gun with a 1 digit larger frame size. The customer could specify gun weight, so the frame and barrels can be thinner than the nominal size.
Another important point is that as frame size increases, the area in contact of breech ,water table and barrels increases, lessening the stress on the hinge and bolt areas. A lesser but important point is that the area of the butt in contact with the frame increases with frame size.
A 1 1/2 or 2 frame gun will probably handle those loads for one or two hunts a year and show little stress. Both your shoulder and the gun will have a less stressful day if you find a heavier ( 8 plus pound) 2 or 3 frame gun.

Best, Austin