These shotguns were built to handle 2.5" Shot loads, even the late 1940's guns still had 2.5 chambers. These guns have been shot from 65 to 100+ years. I sure wouldn't hotrod one.

Having shot a few deer with 12ga round balls I doubt there would be any advantage to a hot loaded 1.5 oz slug out of a cyl bored sxs without sights.

I have a pair of 1940's built Husqvarna 51's and I wouldn't load over 1 oz of shot in them.

Just my $.02

After the first shot the rest are just noise.