How the EOTech 500 Series Became the Blueprint for Modern Holosights
If you've ever mounted a holographic sight on a shotgun or muzzleloader, you're using the direct descendant of the optic Ian McCollum breaks down in this Forgotten Weapons video. He examines a pair of EOTech 502s from the Model 500 series, the early-2000s redesign that turned the earlier 400-series pistol sight into something built for long guns, and effectively set the template every EOTech since has followed.
Key points
- Sealed housing: McCollum explains that the 500 series enclosed the holographic grating behind a front glass window that's purely protective, so the sight keeps working even if that glass cracks or falls out.
- Detachable battery tray: Unlike the 400 series' fixed compartment, the 500 introduced a removable tray running on N-cell batteries, specifically 1.5-volt cells; he warns that similarly sized 12-volt batteries will destroy the electronics.
- Built-in adjustments: Windage and elevation are now adjusted internally by shifting the holographic grating itself, consolidated into one sealed unit rather than moving the whole rear housing.
- Mounting detail: The combo Weaver/Picatinny base uses a single 7/64-inch Allen screw, and McCollum stresses it's an English, not metric, fitting.
- 3D archery reticle: He demonstrates a special archery version with a hologram-based ring reticle that visibly shows when a bow is canted, a trick unique to holographic optics.
Quick take
McCollum frames the 500 series as the quiet turning point where EOTech's civilian hunting optic caught the attention of special forces users, leading straight into the militarized optics the brand is known for today. For collectors or secondhand buyers, the battery warning alone makes this worth watching.
Watch the full video: Forgotten Weapons