Remove one nipple. If it looks like a coarse thread = Uberti SAE U. S. Thread. If fine thread = Pietta Metric
Best option: Take the nipple to ACE, Lowes, or Home Depot. The hardware dept will have a Thread Diameter and Pitch gauge on the wall. Screw the nipple into the test holes.
Again; if Metric, order the Pietta nipples. If it is SAE, order the Uberti nipples.
This isn't necessary at all, the Pietta's are going on the Euroarms cylinder :Ewan said:I did change that on my wife's Remington .36 Euroarms 1973 (XXIX) around three weeks ago and I put six Pietta nipples, I don't think that this could be different for a Colt navy ...