Eotech 553 is 13.2 oz
Aimpoint PRO is 13.0 oz ETA this is with included QRP mount.and flip covers
Eotech 516 is 12.3 oz
Aimpoint Comp M2 13.0 oz, this is with QRP2 mount with 1/3 riser and spare battery cap w/ spare batt
Aimpoint Comp M3 10.9 oz, this is with LT 129 with spare battery
Aimpoint Comp M3 12.9 oz, this is with LT 129, spare battery, flip covers and Rubber cover.
-I now run this optic without any covers! That stuff is way heavier than you would think!
- flip covers weigh 0.6 oz
- rubber cover weighs 1.45 oz
ETA
MRO weights
-bare = 4.25 oz
-Scalarworks lower 1/3 = 5.45 oz
-factory lower 1/3= 5.95 oz
The Scalarworks mount is extremely nice, I bought my MROs without mounts from Aim a few months back for a really good price. However, if I already had the mounts, I don't know that I would spend the extra coin to save a half oz. It is a very nice mount and is more aesthetically appealing than factory, but I think I could spend $150 on ammo or other go fast parts just as well.
Probably would have had more accurate measurements in grams, but this will get you pretty close.