[nikto]

20mm shells pack enough explosive to down jet planes. cut off .50 bmg cases where they start to bottleneck and they are a perfect fit for 10 ga. develope a 10 rd box mag and you'll have something (along with another idea already proven to work with 12 ga),

 

[gripper]

I wonder if an adaptation of the VEPR/Catamount Fury/Saiga based shotguns is doable? Could a rifled barrel be made up to work with these cut down cases? Admittedly, they'd no longer be " shotguns", but THIS is an idea that interests me.

 

[nikto]

rifle a barrel of larger than .50 bore and you've got an NFA item. my interest is in having 3 ozs of "rifle" grenade, with a burst radius of 2m, 3-4 shots per second.