I tried some AR brass in Safariland Comp 1 loaders, rims too thick, couldn't get the loader knob to rotate closed at all.
I had some HKS loaders for AR brass but didn't like how loosey goosey the rounds were held, gave them away.......
Check the NRA Police Pistol Combat Rule Book Section 3 for firearms/ammo requirements.
https://lecompetitions.nra.org/media/8880/police-pistol-combat-rule-book.pdf
There can be variability in case wall thickness which will cause crimp tension variability but not much you can do about that.
As RJH posted, too much crimp can cause significant accuracy problems, so a tighter bullet to case fit will help to prevent bullet creep without having to over crimp.
At least Two possibilities:
Excessively expanded case mouth for bullet seating.
(I use the absolute minimum case mouth expansion for seating plated/jacketed bullets.)
Too little crimp, although the crimp marks indicate pretty good crimp.
Keep in mind that variations in case length can and do change the crimp strength as the case length varies.
Are you able to measure the diameter of the crimped case at the very edge of the case mouth and then determine exactly how much the case is crimped compared to a sized case before the case is expanded for bullet seating?
I have a Nikon 2X pistol scope mounted on the 625 and am firing from sandbags from a sturdy bench, shooting 25 yds. at a black 1 1/2" square aiming point which has a white center about 1/2" square. Holding the cross hairs in the white center of the black square.
The 625 is "almost" motionless but the cross hairs stay inside the white square as each round is fired slowly using single action trigger pull.
This is the same technique that I have used with other S&W revos to develop loads that give 1'" groups at 25 yards; also used same process to fire 15/16" groups from open sights on G4 G21 using Hornady Critical Defense factory loads.