Lots of bbl and cylinder switching on the Colts.
The 3rd Gen bbls had a thread pitch change,so they won't interchange with the 1st and 2nd Gens.
The one-piece 3rd Gen cylinder can be fit to a 1st or 2nd Gen gun.
But you also need to replace the hand w/a 3rd Gen hand at the same time. The ratchet teeth being the difference in the two.
Don't know what or if they did anything different again when they went back to the 2 piece cylinder/bushing around 2000,,or what's interchangeable with what anymore.
3rd Gen Colt SAA bbl threads are within an easy lap-in fit to the Ruger SAA. Once in a while one shows up on a custom job. No real reason, sometimes availability,,sometimes just because.
Easy guns to work on and work over. Anything NIB or close to it I'd keep it that way and sell it to someone that feels it's worth a lot of money because of that.
Used/shooter Colts are always easy to locate if that's what you're wanting. Or make the NIB into a used/shooter yourself through simple handling and use.
The 3rd gen cylinders with separate bushing still interchange just the same. Change if you like but no need to replace the hand w/a 3rd Gen hand even though the ratchet teeth look different on either of the two 3rd gen cyls, with or w/o separate bushing to install in a 1st or 2nd gen gun.
In fact any gen Colt cyl also works well in a Ruger mid-frame, new or old model. 3rd gen barrels have same thread as Ruger, 24 TPI, except some of the Ruger Hunter models.
Colt SAA screw threads by generation vs. USFA and Ruger:
1.) 1st gen, 2nd gen and USFA barrel threads are the same at 20 TPI, while 3rd gens* are 24 TPI (the same as Ruger mid-frame and large frame barrels with the exception of the Hunter models).
2.) 1st gens and Post War/Pre War SAAs (which were assembled on 1st gen frames) use the same screw threads including barrels.
Frame: = 8x34 all six the same.
The grips screw: = 6x38
Ejector attachment stud screw: = 6x38
Black powder frame cyl pin screw: = 6x36 tapered (possibly 6x38)
Hammer = .226" x 24 TPI
3.) 2nd and 3rd gen use the same screw threads**. (also USFA & Ruger except as noted below)
Frame: = 8x36 all six the same. (Ruger = 6x40)
The grips screw: = 6x40
Ejector attachment stud/screw: 6x40 (same as early Rugers with stud on the barrel, but same cap size as later Rugers, .220").
USFA = 8x36 & no barrel stud (same as later Rugers w/o stud including same diameter cap).
Black powder frame cyl pin screw: = 6x40 straight thread. USFA = 6x40 tapered with a smooth pilot tip.
NOTES:
*I was told by a gunsmith who had several NF replacement barrels that Colt 3rd Gen NF's had barrels with the same thread pattern as the 2nd Gen NF's. Maybe Colt had enough left over 2nd Gen NF barrels when they started making the 3rd Gen versions.
Colt gunsmiths can rethread a 3rd gen 24 tpi barrel to 20 tpi to work in 1st and 2nd gen guns, but not the reverse.
I don't have any trigger/cyl bolt screws out of guns right now, but will check next time I do.
**There are no 3rd gen metric Colt SAAs. That myth was started back in 1976 by several erroneous gun rag articles when the 3rd gen SAAs were introduced. It just occurred to me that possibly the Metric 3rd gen myth was also based partly on the fact that the barrel thread changed.
