EOTech 552 (552.A65)

The EOTech 552 is the night-vision-capable AA-powered holographic sight that defined the SOPMOD Block 1 era M4A1. It uses the same 68 MOA ring with center 1 MOA dot reticle as the 512 and EXPS3, and shares the same 5xx-series AA body as the 512 (5.6 x 2.0 x 2.5 inches, about 11.5 oz); the difference that matters is the 552's 10 dedicated night vision brightness settings, which the daylight-only 512 lacks. That twin-AA holographic silhouette is the optic clone builders chase for a period-correct Block 1 / Block I rifle.

The holographic reticle is the technical advantage over LED-projected red dots: the reticle floats on the glass without parallax, stays visible even if the front window is partially obscured by mud or cracks, and acquires faster in CQB than a single dot for most shooters. The 68 MOA ring brackets a man-sized target at roughly 100 yards for ranging, and the 1 MOA center dot keeps precision shots honest. The integrated mount clamps to both 1 inch Weaver and MIL-STD-1913 Picatinny rails using a hex bolt with a thumbscrew, so it indexes onto a flat-top upper without a separate ring set.

For a Block 1 clone or any AR that pairs a holographic sight with a night vision device, the 552 is the correct optic where the 512 falls short. It runs 2x AA batteries for roughly 2,500 hours on lithium (2,200 on alkaline) at setting 12, carries 20 daylight plus 10 night vision brightness settings, and weighs about 11.5 oz. Caveats: the holographic body eats more rail than a micro red dot, and EOTech's 2015 thermal-drift settlement history is worth understanding before buying. Water-resistant to 33 feet, backed by a 10-year warranty, still in production and made in the USA.