[nickelplate]

I recently bought a set of GEN III NOS colt factory walnut grips that are rated by a well known seller at 99% for my 6" B STS Python that originally came with a single black Pachmayr "gripper" grip. In my many searches for the right set of grips for me I have come across several pairs that have been broken on a wood grain line, usually in the lower area of the upper portion of one of the pairs. Could this be due to over tightening the grip screw? Before I begin to tighten down my new wood set, is there a method of determining when to stop tightening the grip screw?

 

[dfariswheel]

There is no standard.
You just use your best judgment about whether the screw is tight enough to prevent the grips from shifting on the frame.
If you have grips that are more then slightly loose, you correct the fit with 5 minute epoxy.

I don't think I've ever seen properly fitting Colt grips that split from tightening the screw too much.
Usually what I'd see on old grips was the wood starting to bulge and splinter out on the inside either on the screw head side or the bushing side.