Same goes for the 20 ga loads equivalent to the 12 ga except the 7/8 oz loads of all types back then were a little more problematic as were the 1150 fps 1 oz loads. The 1300 fps "sporting clays" loads now available might not have issues but they were not available when I had a 303.
Further thoughts, I cannot comment on the use of steel shot loads in these guns as I never tried tried it. They were designed in the days of lead shot and made in the early days of steel shot so performance with the latter could be variable. One would need to experiment a lttle to get a feel for what does or doesn't work well.
