Just installed a CMC adjustable trigger on a RIA mil spec. The trigger seems to work fine but I noticed theres some side to side movement. Apparently theres some space between the frame and the trigger. Is there anything I can do to minimize this ?
Pop the trigger out and check that the two sides of the trigger bow are parallel. If they're cupped inwards it could result in some play. It's going to be infinitely easier to adjust the width of the trigger bow than to adjust the width of the trigger shoe, so that's where I'd start.
Brownells sells a trigger stirrup die that works well on some triggers, but I haven't had luck with the McCormick trigger because of the radiused corners to the rear. It just won't fit on the die properly - so don't waste your money.