I picked up an old English 1880's hammer gun at the Southern this year with 2 1/2" chambers, Damascus barrels, black powder proof, no nitro proof, good walls, no pitting. I have no experience with the 2 1/2" cartridge.
I picked up 2 flats of the RST #7.5 ultra lite 3/4 oz. to shoot at the range to get used to the thumb lever. I was astonished by the number of load choices in 2 1/2" 12 at RST. I count 19 products in this shell specification. My goal is to have the old girl in the field this fall, shooting grouse and pheasant. Advice is requested as to appropriate, favorite/most effective loads to pattern and eventually use this fall.