I also was not very recoil sensitive until around 70 yrs of age when I became more tender. The old British "Rue of Thumb" of gun weight = 96 times the shot weight is a pretty good guide.
This fits quite well with Burrard's rule that most people can generally handle loads that do not exceed 16 fps of recoil velocity. Recoil velocity is actually a much more important factor than recoil Energy. If not NO ONE could handle the really big stuff.
I have shot factory 1¼ oz loads from a 3'' 20 that weighed only 6¼ lbs. Recoil was stiff but bearable if one was only shooting a few & not in rapid succession. When I was much younger I shot some of the 2 3/4" baby Mags with 1½ oz shot from some rather light guns, all solid breech, no gas-operated guns, but would not do so now.
