Of course, you could also attach a rifle stock to an M-19 mortar tube. That would probably kick quite a lot too.
This is where the adjustable pneumatic butt plate comes into play.
In WWII, a fair number of guys broke their legs thinking that ‘knee mortar’ was a description of how to operate it. I suppose you could use it to break your collar bone as well. https://en.wikipedia.org/wiki/Type_89_grenade_discharger