Hi Antique, the Howell (Taylor) .45 Colt 1860 conversion cylinder is known to not allow spec .45 Colt, 1.6", to fit that cylinder. The Pietta version of that cylinder has a maximum COAL of 1.58" (measured). I have loaded all my .45 Colt to a COAL of 1.55" so they fit in my two conversion cylinders. From information on the Kirst site their 1860 cylinder for the Uberti is 0.05" shorter than the Pietta cylinder. If the difference is similar for the Howell, I'm SOL. I'm still waiting for a reply to my emails from Howell and Taylor on the Uberti 1860 COAL.
I suspected that the Uberti 1860 C&B cylinder is ~0.020" shorter than the Pietta, but don't know for sure. If that is the case, my loaded .45 Colt cartridges may still fit in the Howell (Taylor) Uberti 1860 conversion cylinder. I won't know the Pietta/Uberti C&B cylinder difference until I get my Uberti tomorrow.