I have a Henry single shot rifle. I'm using a scope on it so I bought their offset hammer spur. I had trouble with the original Henry one piece scope mount while working up loads. It set the high power scope I was using too low. The optic bell was being struck by the hammer and its spur. It caused intermittent misfires.
I bought a used Redfield 1-4x scope from the internet. It has a smaller optic bell so it worked fine but it put the scope higher than I liked. So I checked the Henry website. They are offering a new picatinney mount that takes Weaver rings. So I bought one and yesterday installed it. I mounted Weaver low rings on it and I had the same problem. The hammer was striking the optic bell of the smaller scope. So I reinstalled thee original Henry mount and the problem went away.
If you decide to put a Henry picatinney mount on your single shot rifle you should use higher rings. Be aware, also, that the Henry single shot rifle will not accept other brands of offset hammer spur because of the shape of the hammer.
I expect this combination to be very good for my carrying. The rifle is not light but it is accurate. It needed a trigger job. That's common with today's single shot break open rifles. Don't reduce hammer spring tension. It can be done with careful work.
Jim