Ruger is going to say that it can't be done, etc etc, or send it in...there are alot of gp100 parts floating around and I suspect that you will need a hammer and a trigger, both of which are common on the net for 15-25 a pop. But like John said, it takes alot of fitting to get it right, and unless you are fairly skilled, or just plain mad (like me) you might have to get the parts and dump 'em on a reputable smith to get it done right. On top of that, used parts were once previously fitted on another gun, so it is a crap shoot whether or not there is enough material for proper fitting.
It can be done, I managed to get a regular redhawk trigger to fit in my SRH, but it took alot of work to get things to function right, and alot of time was spent with am emory board (I stole from my wife) removing microscopic amounts of material, and then alot of dryfiring. The trigger of the gp100 series is a truly fustrating mechanical device, and changes to one part result in the possibility of another part not functioning correctly. Then there is the whole issue of springs, and decreasing the strength of them can throw everything out of whack forcing you to have to start all over again, not to mention that when installed, the tolerances are a little different and the trigger does not move forward as far as it does when the trigger group is not installed, because the hammer and and and...well it can be a real pain.
Not to scare you off. I did it and I am just an average gadget junkie, but I wish I had known what I was getting into when I first started.
