I wonder about relative pressures between U.S. and European .410 ammo. ... It seems that British 3" .410 ammo may generate less pressure than Winchester and Remingtom 2 1/2" stuff.
It seems "pressure" is a nebulous metric with respect to gas-operated shotguns. The reported value is usually the peak chamber pressure and since gas-operated autos work by bleeding off gas off quite a distance forward of the chamber it isn't obvious that a "higher" pressure necessarily indicates a shell's ability to cycle an action.
