The problem is that the hand/pawl channel in the frames varies from gun to gun and manufacturer to manufacturer. In many cases the Ruger pawl plunger is to short and will fall into the hammer channel or hang up in the plunger hole. Rather than continue to fool around with them I have gone exclusively to the following:
Plunger -- Ruger Part Number KE51, Brownells Part Number 780-001-231
Spring -- Ruger Part Number KH05000, Brownells Part Number 780-000-464
These are actually trigger plungers and springs from a double action Ruger.
The plunger and spring are smaller in diameter than the Ruger pawl plunger and spring, but the plunger is longer. I have not found a Uberti or Pietta they do not work in.