I have the USH 20. I had it fitted to a SB1 receiver. I absolutely love it. Now I am biased, I took an 8 point a week ago. He was at 65 yards. Using light fields, went thru both shoulders. It has virtually no kick.
I have always used a 12 gauge pump, but I think that is now changed.
I have not shot the USH in a 12. I heard it kicks like a mule with 3" shells, so I stayed away. I am now glad I did. There are several USH 12 users on the sight, they will be here shortly. Please enjoy the music while you Waite
Lonny