Howdy
The Original Poster asked me to chime in on this one.
What I have to say may be relevant, particularly since somebody has already taken the liberty of posting one of my photos.
I can tell you that for the longest time, Uberti absolutely, positively did not put recoil plates (which is what Colt calls the bushings in question) into their single action revolvers.
I seem to recall reading recently that one of the Italian reproduction companies has started putting recoil plates into their single action revolvers. Not entirely sure which company, I seem to recall it is Pietta, not Uberti.
In any case, for many years, Uberti absolutely, positively did not install 'firing pin bushings' or 'recoil plate bushings' or 'recoil plates', or whatever you want to call them, in their single action revolvers.
Thereby hangs a tale, to quote the Bard.
Back around the year 2000, when I first started shooting Cowboy Action, I bought a used Uberti/Cimarron Cattleman, chambered for 45 Colt. It was finished in what was called their Charcoal Blue finish, and it was beautiful to behold. But it had some problems as I was soon to discover. Messing around with the gun, before taking it to the range to shoot it, I gently lowered the hammer all the way down onto a live round. Let's not get into an argument about whether I should have done that, which clearly I should not have. Anyway, when I went to cock the hammer, the gun froze up. The cylinder was locked in place, and I could not cock the hammer at all. I could not bring the hammer back to half cock to unload the gun because the cylinder was frozen and would not budge. I started to panic because I was in the basement with a loaded gun that I could not unload. Yeah, I should not have been in that situation, as I already said, but there I was. Eventually I was able to very carefully coax the hammer back to half cock. Even so, the cylinder would not spin, and I still could not unload the gun. I pulled the cylinder pin out, and keeping the gun pointed as safely as I could I managed to work the cylinder out of the gun. Imagine my surprise when I saw a deep, fresh scrape across the cartridge head and the primer that had been under the hammer.
It turns out, there was a raised burr around the firing pin hole in the frame. The burr had grabbed the primer pretty tight, and was preventing the cylinder from spinning, which was what bound up the gun. I had been shooting single action revolvers since I was a kid, but this was a new one on me. What had happened, is every time the hammer fell, the firing pin contacted the steel of the frame, and over time it had peened enough metal over to raise a burr around the firing pin hole. Which is exactly why Colt installs a hardened recoil plate in the frame around the firing pin hole. The firing pin in a Colt or Italian replica is mounted in the hammer with a rivet. At least until recently when Uberti came up with their new design with the retractable firing pin, but that is another story for another time. The rivet allows the firing pin to wiggle up and down a little bit. When the hammer falls, the tip of the firing pin moves through an arc centered on the hammer pivot screw. The firing pin hole in the frame is funnel shaped, because it would be impossible to drill a hole exactly following that arc. So the firing pin is allowed to wiggle a little bit in the hammer because it has to 'find its way' through the hole. In the process, the firing pin rubs against the metal of the frame. Over time, as the firing pin rubs against the frame many times it can eventually displace enough frame material to raise a burr, which is exactly what had happened with my Cattleman. That is why Colt installs a hardened recoil plate in the frame. The recoil plate is harder than the frame, and even though the firing pin will still be displacing a tiny amount of metal, the burr does not extend through the hole in the recoil plate. Smith and Wesson installs a hardened bushing in their frames for the exact same reason. This particular Uberti, absolutely positively did not have a hardened plate installed, so the firing pin had raised a nasty burr that was scraping across primes, creating a real problem. I suspect the original owner got rid of the gun because of this, and unsuspecting me came along and bought it used from a shop and discovered the problem.
At first, I took a fine file, and carefully lapped the burr down until it was level with the frame and thought the problem had been solved. Burt low and behold, the burr returned, even though I did not dry fire the gun at all. Just normal firing raised the burr again. So I took a very long drill bit, covered everything but the tip with masking tape, and inserted it down the barrel and turning the bit by hand very carefully put a very small chamfer around the hole. Just a tiny amount. This solved the problem. The burr probably returned, but it was raised up into the void created by the chamfer, and did not interfere with primers or cartridge heads again.
But there absolutely, positively was no hardened bushing in the frame of that revolver.
I eventually sold that gun, because it had other problems.
A few years later I took a chance on another Uberti Cattleman. I was careful to inspect the firing pin hole for any raised burrs this time, and did not find any. But eventually this gun developed the exact same problem. The problem, was not as bad, the burr never locked up the gun, but I could feel a burr starting to rise. My solution was the same, I still had the drill bit, so I repeated the same operation. I still have that Cattleman. Here is a photo of the firing pin hole in the frame. The 'halo' around the hole is a mark left behind by primers slamming back against the frame over and over again in recoil. It is not a pressed in bushing. If there had been a hardened bushing there, my drill bit probably could not have bitten into it. You can see the tiny chamfer my drill bit left around the hole, as well as a couple of small chips it created. No, the chamfer is not big enough to create any problem with primers flowing back and locking up the gun.
View attachment 770626
Here is the photo of the hardened recoil plate pressed into the frame of a 1st Gen Colt. Notice how large it is. About .300 in diameter. They are about the same size in 2nd Gen Colts too. I have not bought a new Uberti or Pietta in years, so I have not seen what they are putting into the frames these days regarding recoil plates or bushings. If the Original Poster's gun that he bought used, is missing a recoil plate you can see how much smaller in diameter the plate was than a Colt recoil plate. No wonder dry firing may pop them out.
View attachment 770627
In retrospect, I do not believe the 'crater' around the Original Poster's firing pin hole was created by hot gas from pierced primers eroding the metal away. The popped out hardened bushing scenario makes more sense to me. But note that the OP states his problem is with Uberti guns, and he has ordered Pietta bushings on order.
I still don't know for sure exactly what is going on here, unless Uberti has started installing bushings too. But they ought to be bigger in diameter and pressed in better.
That's about all I have to add to this post, hope it has been useful.