Now, I've got more money in it than I would have if I'd have bought a springer mil spec, and I still want a beaver tail, better trigger, skel hammer, bigger slide release, different safety... and my gun smith tells me that all of the above will require a good deal of hand fitting, because the fit of the RIA isn't quite up to spec.
I might start looking for a new gunsmith.
The RIA frame isn't out of "spec"...being cast instead of forged, it's beefed up in a couple of places to maintain strength. Some parts may require hand-fitting, but this is partly because of dimensional differences in the RIA frame and the fact that the part was made oversized (for tight fitting) to begin with.
Replacing the trigger on mine required minor filing of the trigger blade so that it would fit in the slot. Not that big a deal, and probably as much the fault of the trigger as the gun.
Skeletonized hammer? The Wilson Combat hammer dropped right in.
Bigger slide release? Drop in.
Different thumb safety? Haven't tried this one yet.
A GI-style gun has to be modified to put in a beavertail? Stop the presses! Of
course the frame has to be ground down to put in a beavertail. That's what those jigs are for. If you've just gotta have one of these, and I think they're a mixed blessing, RIA makes a tactical model that comes with a beavertail.
As for getting a good trigger pull...mine's just over 3 lbs. and very crisp. I put in a new trigger, a skeletonized hammer, a Wolf mainspring and a King's 4-fingered sear spring. Other than fitting the trigger blade to the channel, no alterations were made or required.