Finally got a chance to take it out. It works.
Also got rid of that abomination they call a safety. Tapped the hole 6mm X 1.0 and put in a stainless set screw. Replaced the sling stud that was poking out the bottom with a QD socket up front.
Shot some Gold Dot loads that were worked up for the 16" M7. Only lose 120 fps (2050 vs 2170) but there may some room to go from there once I work something up, as these were not max. 3/4" five shot group at 100, as good as I'm doing on average with the M7. Not bad.
Then shot some cast subs, again loads developed for the M7. Five shots in just under 1.25" @ 100 yards, about as good as it gets for me.
I'm stoked. Looking forward to next deer season.
BTW, there are 10 of these pistols left on Gunbroker. https://www.gunbroker.com/item/797427354