“For most any 12 ga. a load of 3 3/4 drs. of Fg and 1 1/4 oz. of shot will not be too heavy unless the gun is very light, and so loaded, a good 12 ga. properly choked will kill its game just as well as a modern 12 ga. with long range loads.
For lighter work, 3 1/4 drs. and 1 1/8 oz. shot will...