me and a friend used Norma R1 to blow up a short barrel many years ago , it was more like a long thunder mug than a cannon
bored out from a solid piece of steel
bore diameter approximately 30 mm , outer diameter I guess was approximately 100-120 mm
dont remember exact , it was a very long time ago
we used a wood plug
ok guys dont try this at home
or should I say "hold my beer"
well it wasnt as dangerous as it sounds, we had it in a former military bunker when we set it off