As an arbitrary experiment, I switched my standard bullet (Nosler 168 BTHP) with a Sierra Match King, running IMR4895... my groups tightened up, not by much, but even I noticed a difference in my Socom16.I have found that bullet type often times is more important than powder type & load. hth. you might try a better bullet.
I quit the Ultimate Accuracy Chase many years ago, if the load I've worked up shows acceptable accuracy for what I want it to do, then I'm happy, call it a day, and crack open a beer.
OP, I would continue with your load development... I would load some more 41.5grn loads, and maybe 1 or 2 steps higher just to see if there isn't some more obvious improvement to be had. I would also reverse your testing... run the higher loads first, and then back down... to make sure a warming barrel didn't affect your test results, too.