I have loaded 28ga skeet loads in 20 ga hills, for 9yos to learn to shoot. IIRC, used 800-X and shot extremely well.
Used Green Dot on my attempt at the 12ga. May need Red Dot, but 2400 or something for smaller gauge may be the answer.
OTOH, Challenger has a 1 3/4" 12ga loaded with 5/8 oz of 7 1/2s @1200 fps. Case of 300 is $99.99
These would be awesome shooting in a SxS. Not sure how fast reloads would be, if the shorter hull would help, hurt, or not matter.