I WROTE THIS LAST SUMMER AND NEVER POSTED. I WAS WAITING TO GET MY RIFLE BACK FROM WINCHESTER BARRELS BUT THAT IS TAKING WAY LONGER THAN ANTICIPATED. SO I WILL SHARE THIS NOW AND MAYBE SOME WILL FIND THE INFORMATION USEFUL.
Gentlemen – This Winchester 1876 thread has been a wealth of information for me. I purchased a Uberti 1876 in 50-95 a few months ago. It was an impulse purchase and I have a friend that has one in this caliber. Also another has a 45-75. I could have purchased the 45-75, but I wanted something exotic. My friend that has the 50-95 had gone thru all the work to get his to shoot. However, my experiences were totally different.
First, I needed to procure reloading dies. Cimarron Arms, Stoger Uberti and even Uberti in Italy were of no help in deciding which dies to use. Namely CH4D or RCBS. I had asked for chamber drawings, but none could be secured. So, I had to bite the bullet and purchase CH4D dies based on my friends experience and on-line sleuthing.
Secondly, there are no commercially available cases for this caliber, without spending ones retirement income! I ended up forming cases from 50 Alaskan initially. So I formed the cases, trimmed, reduced the rim diameter and rim thickness. These steps being done using a drill press and file.
I slugged the bore and found the groove diameter was 0.517 inches. In fact my friends grooves measured 0.515 inches. Interestingly, the bore diameters were nearly the same (within tolerance). So it seems that my grooves are deeper than his. He had Accurate Molds custom make a mold (51-350CL) for him. However, this bullet measures 0.72 inches long and must be driven to velocities exceeding 1,350 fps or faster to stabilize in the 1/48 twist Uberti uses. He had found a good load using Trail Boss, as well as 5744, so it used that bullet in my 50 Alaskan cases. At 50 yards I had a “pattern” of a foot.
I noticed using the 50 Alaskan cases and the CH4D dies, that the seating die was swaging the neck. I pulled a loaded round and found the bullet had been reduced in diameter to 0.511. The Alaskan case necks are too thick. The inside neck diameter needed to be reduced to the thickness of Jamison cases. This necessitated purchasing chucking reamers to accomplish this. But a Jamison neck is really thin. So this sort of worked, but not well.
Back tracking I purchased some 50-90 Sharps cases and formed those. The next wall thickness is less than 50 Alaskan, but still could not be run all the way into the CH4D seater without swaging down the bullet. So the seating plug was modified to allow the bullet to be seated without entering the neck portion of the die. BUT now I could not crimp. I next purchased a 50-70 seating die and that alleviated that problem.
With all the trials and tribulations of the case dilemma, I still was not getting groups less than 6 inches at 50 yards. So I decided to do a chamber cast (which I should have done in the beginning). Interestingly, the bore size was confirmed at 0.517 inches. Also, the neck diameter of the chamber measures 0.537 inches. HUMMMM. Same as a 50-70. Interestingly enough, the neck diameter of a cartridge loaded in CH4D dies measures 0.532 inches. Using cases with the proper wall thickness and bullet diameter, asking the bullet to bump up 0.005 inches is asking a lot. Especially with a bullet that is so short for the diameter. In order to get proper accuracy, the bullet, in this situation, HAS to be bore diameter of slightly larger. You cannot rely on bullet bump.
So now I can use my “unreamed” 50-90 cases and a 0.517 bullet and chamber the round. The case bullet combo being as good as it can get for accuracy. However, I was still not getting good groups. The round pattern was smaller, but now a couple of inches wide with vertical stringing.
Inaccuracy from the beginning was primarily caused by a poorly assembled rifle. Specifically, the forward magazine tube ring was loose on the barrel. The nose cap retainer would fall out of the dovetail (it was not tight). When the rifle was assembled, the tech cranked one of the nose cap screws down firmly, essentially pulling the retainer up tight against the magazine tube. Also the length of the magazine tube was a few thousands to long. Another factor is the handguard had to be levered into to place. All these deficiencies imparted stresses on the barrel. There are some good you tube videos on accurizing lever guns and this was a great help to repairs these problems.
By properly fitting the handguard and magazine tube to the barrel and provided a cartridge to match the chamber is was able to get the rifle to shoot groups at 50 yards in the less than 3 inch range. However, this is not where I want to be. I really want to see groups under 2 inches at 50 yards.
As a foot note, my rifle has a 1/48 inch twist. This twist is on the ragged edge for stability for a 0.72 inch long bullet. Anything longer will not give the best accuracy. I have purchased a mold from accurate that is 0.67 inches long and I should be able to stabilize that bullet down to a velocity of 1250 fps. Sure would have been nice if Uberti would have made this in a 1/42 twist!
Forward to 11/4/2020, I sent the rifle onto Winchester Barrels to have a new barrel installed. Groove diameter of 0.512 and a twist of 1/32. I am still waiting for my rifle and parts to be returned as of 5/27/21. But that is an entirely a different saga.