"...There has been improvement..." Yep. They're not paper any more either. Paper apparently saw a rain cloud and started to swell.
"...higher performance..." Isn't required for something firing little round balls and is designed to produce a pattern not a group. Said little round balls fly like bricks.
"....303 British and 7.62x54R..." Both of which work just fine through MG's with box mags too.
Rimless cartridges date from the 19th Century too.
"...semi-auto shotgun with a box fed magazine..." Semi-auto nothin'. Several mag fed FA shotguns around.
"...higher performance..." Isn't required for something firing little round balls and is designed to produce a pattern not a group. Said little round balls fly like bricks.
"....303 British and 7.62x54R..." Both of which work just fine through MG's with box mags too.
Rimless cartridges date from the 19th Century too.
"...semi-auto shotgun with a box fed magazine..." Semi-auto nothin'. Several mag fed FA shotguns around.