I understand that!! (I've never messed up, of course
)
I've done two grooved narrow triggers and one wide target (leaving three smoothed over grooves down the center for "tactile reference") and I've touched up the ends and edges of all of my "combat" triggers. Using Cratex polishing tips in the Dremel (fine or med. grit) gives you a slow cut which you can monitor closely. I slip the tailof an old T-Shirt into the triggerguard to catch any overruns, and tape part of it over the frame opening. With the Dremel on a speed control, it is possible to take the metal down a thou at a time, and still have very good control. It's a case of slowly, slowly catchee monkey.
I use the same wrap and tape if I'm using carbide paper, but it is work in ten-thousandths, and takes more patience. ALL of my triggers out of the box try to bite me with the end of the trigger, and I've even had to smooth the end of a 686 from the Peformance Center.
I have seen replacement hammer and trigger sets from the factory that were supposedly "drop in", but this was several years ago, and , frankly, the idea seemed preposterous given that these parts are at the heart of the timing process.