Howdy
First off, if you bought the gun used there is a good chance somebody has lightened the hammer spring. Lots of Cowboy shooters, myself included, do that. It is easy to lighten it too much. Did you buy the gun used?
Second, look to see if anybody has placed a spacer between the main spring and the frame where the spring screws to the frame. Putting a spacer there is a well known way to reduce the hammer pull.
Third, don't try to figure out what's wrong with questionable reloads. Eliminate the unknown factors. Use factory ammo. If they are reloads, how do you know the primers were seated properly? A very common problem with reloads is the primer is not seated all the way and the firing pin expends some of its energy seating the primer before the primer fires. This can create misfires. A shallow dent on a primer may be from a weak spring, it may be from an improperly seated primer. They look the same. Check the ammo to see that the primers have been seated properly. They should be just a couple of thousandths subflush to the case head, they should not be proud.
If you reload your own ammo you can just use primed cases to test hammer spring strength, I do it all the time. However be aware that a fired primer in a primed case with no powder or bullet will tend to back out, jamming the gun up a bit. This is normal with firing primed cases.
Craig C is correct as usual, most Uberti guns, rifles and revolvers, come off the line with hammer springs that are too strong. I have never seen one that is too weak.
If in doubt about the hammer spring, don't try to rebend it, you will probably just make it worse. You can buy a factory spec spring from VTI replica gun parts. They have springs for all the Uberti products and can sell you the correct one. They know their products very well.
http://www.vtigunparts.com/
If you decide you want a lighter than normal hammer spring, you can buy one from Wolff. I have bought many springs from Wolff.
http://www.gunsprings.com/
For what its worth, Winchester primers are halfway on the hardness scale. Federal primers are the easiest to set off. I know some CAS shooters who tune their guns so finely that they will only reliably set off Federal primers, these ultra tuned guns will sometimes not set off Winchester or CCI primers reliably.
Again, did you buy the gun used?
I have no comment to make about the hammer safety in Uberti revolvers. They seem to be pretty reliable, I have not seen them make any difference. My Colts do not have such a device.
P.S. Looks like you were typing while I was. Did you buy standard springs or reduced power? For normal, informal shooting standard springs are fine. Reduced power springs are for competition, or if you like the gun to be silky smooth. But just replacing springs is not the same as an action job.
