I have been searching for the answer to this but could not find anything. I have an Aimpoint Comp M4S and the only way it will fit in the rifle rack on my patrol unit is to take the spacer out. I feel like it may be too low but i’m not too sure does anyone have any advise. I have not been able to shoot it yet with or without the spacer. Would I have any problems getting it sighted in without the spacer? Thanks in advance for any info.
Shouldn’t have any issues without the spacer it will just wont have a lower 1/3 with your back up sights.
I think with the spacer it’s suppose to be co-witness.
Yes, with the factory spacer it’s absolute co-witness with a flat to upper and a FSB.
The optic will mechanically zero without the spacer but I doubt you’ll be able to smash your face into the stock hard enough to use it like that.
M4S works (somehow) without spacer on HK416, because of higher rail. On “regular” AR15 style rifle it will be to low for use. In this case spacer is mandatory.