Now I am no fan of ARMS mounts, so I’m pretty biased about that. I have this MK12MOD1 upper where I use the period correct ARMS 12H rings. I generally try not to remove QD scopes unless I have to, especially so with ARMS mounts.
On Saturday I found that after having removed the scope and reattached it previously, my zero had shifted 4 inches left at 100 yards. I figured this was a fluke and seemed excessive even for ARMS, so I removed the scope, cleaned the upper and mounting point on the scope rings, and remounted it. That moved the group 2 inches right and an inch down.
Quick detach mounts are awesome, but make sure if you use one, that it does return to zero. I am going to stick with Larue mounts on any of my serious use ARs.