So this is a direct-milled Glock RMR slide and a new 407. There is a gap both around the recoil lugs, and behind the screws. Total points of contact are lugs to optic at the front, optic to slide around the screws, and back end of the optic to slide. Optic did not feel wobbly when first putting on so I think the recoil lug fit is pretty tight. I see some chatter online about the lug holes in the holosuns not being deep enough.
I am reluctant to file the lugs on the slide as it is a hard to get factory rmr gun, and it's clear the optic is not 100% flat on the bottom anyway due to the various bits not being flush. Gun came with a milled steel plate cover that fit well, so I do not think there is a problem with the optic pocket. Is this concerning enough to not try this optic setup, is it a return to holosun, etc.?