Do you mind sharing what bullet and particulars? I've never been able to get a Uberti 45-75 to shoot that good at that distance using MVA sights and a multitude of different bullets. From my personal experience an original Winchester 76 still in good condition will outshoot the Uberti any day of the week with black powder at long ranges.
Cliff
a general comment first -- my rifle likes fat boolits it shoots just average with anything sized .458
Did some scratching around - that group would be shot when I was playing with single loaded heavy boolits and would be the CBE 535 x 459 (their pedersol sharps boolit - but I had it shortened by one groove to 470 grain) so its loaded just on the lands - 72 grains of my FFG willow powder and a HDPE wad.
Have not yet got this gun properly sorted, it strings shots vertical as it warms, (most lever guns do I think)
My more conventional loads are made using the LEE 459x405 HB - thats a nose pour mold designed for the trapdoor - I flattened the nose in the mill for safety in the magazine of the 76 and took the tit off the base plug so's I could use an over powder wad - still weighs 405 grain . I made another base plug that shortened the boolit by one groove to weigh 330Grains - this mold drops at .460 maybe a fat .460 and I use a .460 size die or unsized even
Have a Chiappa 86 that just loves the 330grain version of this.
So below is a 50 yard ten shot string with the Uberti and the 405 grain LEE (shot from the magazine) I pulled a couple to the left but shot 8 pretty good but you can clearly see the vertical stringing - barrel was pretty warm at the end. Shot to shot cadence is the only way I have handled this so far - tried a magazine tube with no front connection - got some improvement but not fixed.
Guys tell me these are pedersoli barrel and it looks like one, beautiful finish inside, a dream to clean.
My brass is reformed 348 winchester - I dont resize , dont even neck size, this brass in my gun, with those fat boolits is just a dead neat fit at the neck end - just enough clearance to allow boolit release and I just reload and put a little crimp on - after about six reloads the case needs just a touch at the rear end where solid head meets case wall - made me a special die for that - just a tiny touch is all it needs. I have two LEE full length resize dies still not used - they are way too savage on nicely formed brass .
bottom pic here is ten with the 470 grain CBE I was talkin about - pulled one low (or maybe thats cold barrel shot?) others are not so bad
All my strings are shot with no clean between shots - so far have refused to do that but I reckon that would eliminate that stringing I get.