Jubal;
Thanks for the reply. This has all been very confusing because half the folks at Buffalo arms say it will hit the bolt and half say it will not. I dont know how much actual experience they have with this, but I tend to be more comfortable taking the advise of someone that has actual experience with what does indeed work such as yourself. marbles has a couple of charts; one for standard peep sights and one for improved peep sights. The improved chart sights have the ability to select different length uprights and you order the base and then what upright you want. Wheras the standard, you just order the whole unit. The one you said caused thumb interference I believe is listed under the standard chart because it says it is for the Winchester 1876,1886 (Orig) and is part no. MAR 009801. The same chart has one that says Uberti 1873(not hunter)1876 part no. MAR 009832. Could that be the one you have? Or, do you have the "improved peep tang sight" with the different upright lenghts option?
many thanks
Big Zwey