We talked, one time before, about target (the black part) size vs. the dot size. I think you changed targets, or mentioned that you had a target that was a better size (don't remember what it was.)
What size are the dots in your optics?
When I was younger and poorer I used to make targets. An old Planters Peanuts can with the bottom cut out, paper/pages torn from old Shotgun News magazines and a can of bright orange spray paint. Lay the can on the center of the paper and give it a shot of orange paint, lift the can and let the paint dry. I wasn't trying to match the size of the orange to anything in a scope or pistol sights, just making myself cheap targets.
Back to the dot and the target size. Would it help if your aiming point was just big enough to see an edge all the way around the dot?
I just realized this might be tough with a pistol dot unless it's sighted in for 100 yds. vs. using a hold over. Or on a windy day. Just a thought. Not even sure what colors would work best with a red, amber or green dot.
Joe, I'll bet what you're doing can be a lot of fun, even on a day when the holes are showing up where you want them. I haven't done any long range handgun shooting in almost 40 years. I'm sure it was much harder than it seemed at the time, then again my eyes were perfect and my hold was a lot steadier - and the triggers on my S&W revolvers were pretty awesome, too.