Shhhhhhotgun Silencer

I thought I'd heard of this a while back... But that it shot slugs best and there was some kind of issue with shot (like the cup opening up in the can?). I don't know how they resolved this here, but if it's legit, then kudos.
 
The 60's were such a blurr. What with all the free love, drugs and rock 'n roll. Guess I was too busy being fed and having diapers changed. The parts I do remember were of terrorizing my neighborhood with my Big Wheel, playing in the sand box and swimming pool.