Good luck with getting that scope on the USH. I tried one with high rings and the power ring kept hitting the top of the hammer when positioned where I wanted it. Ex high rings might work, but I never tried them. If you haven't bought the scope already, try a different scope that has a smaller ocular bell and power ring. I have used the 1-4 Leupold 0r the 1-3 Weaver. Both these scopes are 20mm, with a small bell and power adjuster and work with high and/or sometimes medium rings. In my experiences they are real nice scopes with enough eye relief to boot, especially the Leupold.
In the H&R centerfire section look under the thread started by Duce labeled FAQ's This thread if you scroll down will give you all the info you would need on any shotgun question or handi-rifle question for the most part.
