OK, Here's my second report. Took my one of my Uberti 1861 Navies out with the new nipples. Also took a Pietta 1861 Navy that did not have the safety notch in the hammer filed in.
I rechecked my measurements on the Pietta and Uberti nipples and came up with theses results.
Factory nipple - .292
Treso nipple - .305
Slix-Shot nipple - .320
Factory nipple - .326
Treso nipple - .327
Slix-Shot nipple - .330
In the pictures in the original post, you can how much longer the Slix-Shot nipple is than the factory and Treso nipples.
I spent part of Thursday afternoon running a box stock .36 Pietta with the new nipples, and trying a set of the Uberti nipples. The Pietta is a 1991 vintage 1861 Navy with 6 inch barrel that is internally box stock. The only mods done to it are GWII grip frame and grips. The Load was 22 gr fffg Grafs, lubed wad and .380 cast round ball. I ran a cylinder full through it using Rem#10, Rem#11, CCI#11, and RWS1075 caps. Had a little different result with expended caps than I did with the 1860 the other day. The Rem#10s all stayed on the cylinder but were not evenly exploded. The Rem#11s also stayed put and were more even. The CCIs only split into two wings, some stayed on & some fell off. The RWS caps were by far in the worst shape, they were mangled pretty bad & mostly fell off. I'll attribute this to the safety notch not being filled in. You can see where the notch was on the expended caps.
Tried the Uberti nipples on a Uberti 1861 Navy. Same load as the Pietta, 22 gr fffg Grafs, lubed wad and .380 round ball. Being longer than both the factory and Treso nipples, I expected them to have fitment issues. Sure enough, after 3 cylinders full on the 1861, the Rem#10 caps started dragging the recoil shield. Same held true for the Rem#11, CCI#11, and RWS1075 caps. In order to keep the caps from rubbing, I had to use a push stick to seat them. The CCIs rubbed the recoil shield the most even after pushing them on. The way the caps split and shredded was pretty much the same on the Uberti 1861 as the Pietta. The JB weld has worn away some on the hammer so there was some notch present.
I got rained out before I could shoot the other two Ubertis I brought - a Navy Arms Frontiersman & a SS 1860 Army; but, given the length of the Uberti nipples, the result would have probably been the same. I screwed a couple of the nipples in on the Frontiersman and the tops extended above the rim of the cylinder. I also did not get a chance to try out a reduced power mainspring.
I'm not near as enthused about the Uberti nipple as I am the Pietta.
Fingers (Show Me MO smoke) McGee - AKA Man of Many Colts - Alter ego of Diabolical Ken; SASS Regulator 28564-L-TG; Rangemaster and stage writer extraordinaire; Frontiersman, Pistoleer, NRA Endowment Life, NMLRA, SAF, CCRKBA, STORM 327, SV115; Charter member, Central Ozarks Western Shooters
Cynic: A blackguard whose faulty vision see things as they are, not as they should be. Ambrose Bierce