How to mount a Trijicon RMR HD on a Picatinny rail: it is a Trijicon RMR / Holosun C open-emitter reflex, so it takes a RMR-footprint Picatinny mount. Which mount to buy and the height to pick.

Updated 05 September 2026.

Scope Mount Finder / Every rail, tube and red-dot footprint

Fit a Trijicon RMR HD on a Picatinny rail

Name: Fit a Trijicon RMR HD on a Picatinny rail: published specification
Creator: Scope Mount Finder
License: https://creativecommons.org/licenses/by/4.0/

The Trijicon RMR HD is a Trijicon RMR / Holosun C optic. Here is the mount that puts it on a Picatinny rail and the footprint it must match.

Direct fitThe Trijicon RMR HD is a Trijicon RMR / Holosun C open-emitter reflex, so it mounts on a Picatinny rail through an RMR-footprint Picatinny mount. Buy the RMR-footprint Picatinny mount, not a mount cut for any other footprint.

OpticTrijicon RMR HDTrijicon RMR / Holosun C

interface

MountRMR-footprint Picatinny mount

seats on

RailPicatinny rail (MIL-STD-1913)5.23 mm slot, 10.01 mm pitch

Fit readoutBench figures

Fitment

Optic type

open-emitter reflex

Mount the Trijicon RMR HD

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The Trijicon RMR HD is cut to the Trijicon RMR / Holosun C footprint. To put it on a Picatinny rail you fit a RMR-footprint Picatinny mount: the mount carries the Trijicon RMR / Holosun C pattern on its top and clamps the rail below, so the sight screws down to the pattern it was made for.

A mount cut for a different footprint will not take the Trijicon RMR HD. Match the mount to the Trijicon RMR / Holosun C pattern, and pick the mount height for the cowitness or heads-up hold you want on the rifle or carbine.

Related fitments

›Trijicon RMR HD footprint and mountthe optic
›Trijicon RMR / Holosun C footprintthe pattern
›How this footprint reaches a railthe general fit
›Picatinny rail (MIL-STD-1913)the base

Questions and answers

Fit a Trijicon RMR HD on a Picatinny rail?

The Trijicon RMR HD is a Trijicon RMR / Holosun C open-emitter reflex, so it mounts on a Picatinny rail through an RMR-footprint Picatinny mount. Buy the RMR-footprint Picatinny mount, not a mount cut for any other footprint.