Didn't say you did. Re-read my posting. Pressures of modern 3" shells are indeed loaded to SAAMI specs (which weren't in existence in the 20's by the way), but as you alluded the pressure impulse is much longer and hence has a much longer time to exert its force on the action. Simple fact: if one subjects these old shotguns to a steady diet of modern 3" shells things wear out quicker and they will get loose quicker.
The guys name is moot. He died 11 years ago. He goose hunted hunted with us for years, shooting whatever 3" magnum steel loads were on sale. We advised him repeatedly that he was subjecting that poor gun to a lot more abuse than it was ever intended for. When his widow offered that gun to us (our private little hunting club) as a token of friendship, it was so far off face that you could slide a business card between the barrels and the standing breech, plus the bottom rib was loose over half its length and the chokes (which had the standard factory boring Hunter Arms used on these models- full and full) were out of round, the right one was visibly bulged, and the bores were visibly scored. On top of that there were two fresh tang cracks due to the incessant beating it took.
My personal waterfowl gun is also an Ideal grade Smith Longrange model which I have been using exclusively for six years now. Even though it is chambered for 3" shells, not a one has gone down the pipes. Hand loads in 2 3/4" hulls using 1 1/8-1 1/4 ounce loads of either Bismuth or Nice Shot at 1200 fps keep my freezer full of Mallards and Canada Geese, and my gun has no tang cracks and is as tight as the day it left the factory in 1924 (one of the very first of that model they made).
