Check the sear length. A sear that has been worked on in an attempt to lighten trigger pulls can become too short to hold the hammer back far enough to get a full swing. Take the bottom plate off and see if the right hammer is as far back as the left.
You can check for this condition by just taking the bbls off and looking down into the action at the cocking arms of the hammers.
They should be pretty much even when in the raised (cocked) position.
If one hammer arm is lower than the other, that hammer is not rotated back as far when 'cocked'.
Then you'll have to remove the trigger plate to see why it is so.
Could be a shortened sear nose, or an altered sear notch in the hammer itself.
Repairs or attempts to gain some sort of benefit in trigger pull can be the causes/need for the work having been done.
One other quick check,,Dry fire the right bbl with the bbls off.
Then very carefully check the protruding firing pin and see if the pin (which is a one piece solid part of the hammer) can be wiggled back and forth
at all. Or if it can be pushed back into the frame even a small amt.
There should not be any movement to the pin. They are not rebounding hammers.
It should be down hard against the frame under the coil main spring tension.
Even in the hammer down position, there is a lot of pre-load tension on those main springs.
If you can move it at all, that points to the mainspring, mainspring follower, or even the hammer being stalled at some point before the hammer reached full'down' position
