Zonie - thanks for the reply. I appreciate your taking the time to help. This nipple thing has begun to take on the appearance of an obsession with me.
The Dixie catalog says the Uberti Walker and Dragoons use a 6mm X .9 nipple...Are you sure your gun uses a 1/4-28?
Yes, absolutely certain. I have two Dragoons, one is a Uberti 2nd Model with a date code of 1981 and the other a Colt Signature 3rd Model of unknown age. Both take a nipple with 1/4x28 threads; one is 0.610" long and the other is 0.633" long. Measured with calibrated dial calipers, two different hole gauges and thread gauges. No question in my mind about the result. And both accept a Treso 11-50-01 (which is 1/4x28x0.635) replacement with no difficulty.
I checked the Dixie online catalog and it shows two Dragoon/Walker nipples, p/n's NP0305 and NP1320; the NP1320 is spec'd as 0.245x28, certainly closer to 1/4x28 than M6x0.9mm. I can't find where they call out a M6x0.9mm nipple for the Dragoon.
My thread standards don't show an M6x0.9mm thread in either
ISO Coarse or
ISO Fine. And I can't find an M6x0.9mm nipple in Thunder Ridge's chart, so I'm a little confused by that spec.
The Dixie catalog goes on to say that the Uberti 1862 Police uses a 5.5mm-.9 nipple...The Dixie part number is NP2040.
Yep. Agree with that. But again, my specs don't show an M5.5x0.9mm thread, nor does the Thunder Ridge chart list such a nipple.
A 5.5mm male thread should be .2165 maximum in diameter. Assuming the metric tolerances are similar to the UN tolerances, the minimum diameter for a 5.5mm male thread would be .2100.
This by the way is almost exactly the same as a #12-28 thread. At least, the tolerances overlap for both the diameter and the pitch (28 TPI vs 28.222 TPI).
Agree with that also. Doing the arithmetic, the M5.5x0.9mm thread is virtually identical with 12x28, so I presume that's what Dixie's NP2050 really is. And there are plenty of those in Thunder Ridge's chart, and that's what they specify for the Ubertis as well. So all that makes sense.
That nipple is also used in the Uberti 1851 and 1861 Navy, the 1860 Army, the 1849 Pocket, Baby Dragoon and .36, .44 Remington.
Yes, again. The 12x28/M5.5x0.9mm nipple fits just fine in my other Ubertis, as both Dixie, Thunder Ridge (and others) claim.
If the nipples in your 1862 measure .200, IMO either your measuring device is out of adjustment or the nipples have a lot of wear on them.
I wish it were that simple. The gun is brand new, unfired, with a date code of 1997. I'm sure that this is the first time the nipples have ever been out of the cylinder. My tools are calibrated (by me, so they could be wrong, but I'm pretty sure they're ok) and they correctly measure the threads on nipples from all my other guns and brand name ones I've purchased from Track of the Wolf, Thunder Ridge and Jedediah Starr.
Not only do the nipples (all 5) I've removed from the cylinder measure 0.200x28, but the holes (all 5) in the cylinder measure undersize as well. And I've tried to insert several different nipples that measure 12x28 into the holes with no success - they are simply larger in diameter and will not start, with or without using a wrench. I tried nipples from other Ubertis, Treso's that I've bought from Track of the Wolf and Jedediah Starr and some of Thunder Ridge's house brand. Nothing will fit. Very frustrating.
I'm about to run a 12x28 tap down the cylinder holes and just make them the "right" size. I hate to do that to a cherry gun, but if I ever need to replace these nipples I guess the gun won't be so pristine any more so it won't matter as much.
I'm beginning to question my sanity here. It's not that I need to replace the nipples in this gun (as I said, it's brand new unfired), it's that I can't replace them. And the measurement of 0.200 is just bizzare - that doesn't fit anyone's spec anywhere.
Oh, well, everyone needs a hobby.
Thanks, again, for the response. I'll let you know if I ever solve this.