Hi GyMac, you said: "I shoot one-handed at 25 yards with my 2 Ruger pistols, a 5 1/2 inch Bull Barrel with the .125 inch front sight and a 4 3/4 inch Standard with the .10 inch sight. I find that I can shoot the Standard better than the Target and I think I've traced the difference to the width of the front sight. I'm thinking about having the front sight on my Target milled to .10 inch; I've already got a rear sight leaf in that width. Has anyone else had this experience with being able to shoot better with a narrower front sight? "
Instead of giving you suggested dimensions, I'd like to give you a concept.
For some time now(many decades) international and NRA bullseye competitors
have favored a front blade width that visually matches the width of the bull as
seen when aligning the sights. The rear notch should be wide enough to give
ample width light bars for the lighting(shooting range) conditions.
A feature that is sorely missing from domestic target pistol rear sights is the
adjustable width notch found on international ISSF class pistols. Examples are
the Pardini SP, FWB mod 93, Morini CM22 series and Benelli target pistol series;
to name a few. Anyway, I hope this info helps you with your sights choice.