Holosun 507C X3

The 507C-X3 uses the Trijicon RMR footprint and bolts straight to any slide cut or adapter plate on that pattern. Holosun specifies 1.7 Nm on the mounting screws, which works out to roughly 15 inch-pounds.

Screw length is the part of this job that actually fails guns. Holosun's safety notice is explicit: use only screws that are long enough for the threads to grip deep into the slide, or the sight can come loose under recoil. That means matching the screw to your specific cut depth rather than grabbing whichever pair is closest to hand, and it means a screw so long it bottoms out before the optic clamps is just as wrong as one too short.

The 507C-X3 takes a single CR1632 3V lithium cell in a side-loading tray, so the cell changes without unbolting the sight and without disturbing zero. Holosun rates runtime at up to 100,000 hours on one battery at brightness setting 6.

One CR1632 ships attached to the second page of the printed manual. Holosun specifies CR1632 as the only acceptable power source for this sight, and the tray carries a seal ring that is what earns the housing its IP67 rating, so look at it every time the tray is out.

Elevation sits on top of the housing and windage on the right side. Both are slotted screws, and the included double-ended tool has a Torx end and a slot end: the slot end is the one that turns the turrets. Each click is 1 MOA, which Holosun quotes as 29 mm at 100 m, so roughly 1 inch at 100 yards, 1/2 inch at 50 yards, and 1/4 inch at 25 yards. Total travel is 50 MOA from center in each axis.

Turret direction on this sight runs opposite to the habit most shooters carry over from rifle scopes, and it is worth reading twice. Clockwise on elevation LOWERS point of impact. Clockwise on windage moves point of impact LEFT. Turning the way that feels correct will walk your group further from where you want it.

Both buttons sit on the left side of the housing. A single press of either "+" or "-" powers the sight up, and it always comes up in auto mode. Pressing "+" and "-" together powers it down.

Auto mode drives reticle intensity from the solar cell plus a forward-facing light sensor that Holosun added on the X3 for faster adjustment as you swing between light conditions. Manual mode exposes 12 brightness settings, 8 daylight and 4 night vision compatible, plus an off position for 13 stops in total. Holding "+" for three seconds walks the sight through auto, then manual, then a locking mode where short presses no longer change anything, then back to auto. The LED blinks once at each transition.

The 507C-X3 carries Holosun's Multi-Reticle System: a 2 MOA dot, a 32 MOA circle, or both together. Holding the "-" button for three seconds advances one step, and each additional three-second hold advances another, so you cycle until the reticle you want appears.

Shake Awake drops the sight into sleep after 10 minutes without movement and wakes it instantly on motion. That delay is programmable across four steps, and the fourth turns the behavior off entirely.