I have an 1858 New Model Army steel frame made by Pietta and am using the R&D coversion cylinder for .45 Colt. Bought it from Taylor's & Co. about three years ago. It works well but shoots higher than the .44 black powder ball. I have the target sights so it wasn't a problem making the adjustment.
While it wasn't cheap it works well and I haven't had any problems shooting Remington 250 grain LRN (R45C). The reason I converted it is so I could use it deer hunting. The 45LC is a legal big game cartridge here in Minnesota.
Bersa Thunder 380 DuoTone
Bersa Thunder 45 UC Stainless Steel
Uberti Millenium 45 Colt
Pietta 44 Black Powder w/RD Conversion to 45 Colt
Remington 870 12 ga 3 1/2" w/custom LH offset 3x9x40 scope
Browning BPS 10 ga 3 1/2"
Combat Engineers - "Doin' it in the dirt!"