TargetTalk

For me, I was hesitant to make modifications to my grips for many reasons.
1. If i modify the floor of the palm shelf at the rear of the grip with a relief cut for my wrist does that make the grip illegal, since part of the grip would curve up slightly?
2. How tight or how loose should a grip be.
3. How well does quick wood bond to wood? Will it fall off during a match? That would likely result in a poor outcome.
4. How many points could potentially be hiding in a better fitting grip? How much will it really affect my scores?
5. What modification tools are appropriate for this project?
6. Which part of the grip should I start on first: shelf, fingers or . . . ?
7. If i modify it, the color and texture will look different / uglier. I spent a lot of money on an expensive and pretty tool.

But once i started making modifications, there is no stopping. Making the tinest modification to one part of the grip, leads to wishing another part felt different for greater comfort. That leads to sanding, dremeling and filling. Now my athletes are asking for help making changes to their grips. Go slow! Make small changes. Test frequently. Make more changes.
I recently bought a variety of small / medium ball bearings from 1/4" up to 3/4" for working the putty into a smooth radius shapes to fit the hand. More experiments on the way.

To answer my own question about potential improvements in match points from a grip change . . .

One of my athletes has been shooting precision air pistol for almost two years. She has had her own air pistol for almost a year of that. Her overall scores have been pretty consistent match-to-match, but a lot of variation within the match. She has extra small hands and I have felt that she needs to use 'too much' grip effort to hold the gun because of the poor fit to her hand. She can't relax enough during the match. Because it is an OLD gun, there is not very much of a secondary market for these grips.
Two sessions later of adding 'Quick Wood' wood putty to re-size the grip to fit her hand, and subjecting it to the belt sander to size it back down to fit the ISSF box she shot her match.
Wow. Score jumped from high 480's to mid 500's and resulted in a very happy athlete. Adding fire and motivation. The other noticable improvement was seeing less variation in score from target-to-target.

Your mileage will vary!