Had not yet sent them back, Thingmeister called me this evening. He had me lightly sand the top pad on the right grip w/ 320 grit sandpaper, and that appears to allow the trigger to slide smoothly into the sear & trip it reliably. Lots of dry firing over the next few days. I also filed a very small semi-circle out of the top rear of the left grip, roughly opposite the safety disc, and then applied hot glue to that area to replace the tab on the factory grips that directly bears on the safety arm. That gives me a more positive safety, albeit it's the standard HiPoint mush rather than smartly clicking detents. We'll see how long the hot glue holds up, might eventually go to sawdust & superglue or summat.
Cheers to Thingmeister for fast & excellent customer service.
Still troubleshooting, & Thingmeister volunteered to take the poor thing in & give it some expert love & attention. It's enroute, will report his findings & when it gets back to me and I can rub the grips down w/ BLO.
He got it, and miracle of miracles, the problem persists for the troubleshooter. If I shoot gangsta w/ my right hand, the trigger bow is pulled down by gravity, hits the sear bar, & everything works fine.
If I shoot gangsta w/ my LEFT hand, the trigger bow drops just PAST the sear bar, & dead trigger - and sad dead sinister gangsta. He's able to reproduce the issue.
I told him I was fine if he'd just install some gangsta sights on the right of the slide.
Actually sounds like the opposite, too tight up front making the trigger bar kick out to the right, I think, if I understand him correctly. He says right and sinister gang shooters work equally well now.