Scope Mount Finder

How to mount a Holosun 509T X2 on a Weaver base: it is a Holosun 509T enclosed-emitter reflex, so it needs a Weaver-compatible Holosun 509T mount, not a Picatinny one.

Updated 05 September 2026.

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

Fit a Holosun 509T X2 on a Weaver base

The Holosun 509T X2 is a Holosun 509T optic. Here is the Weaver-compatible mount it needs and why a Picatinny footprint mount may not seat on a Weaver slot.

Direct fitThe Holosun 509T X2 reaches a Weaver base through a Weaver-compatible 509T-to-RMR adapter plate on an RMR Picatinny mount. A Picatinny version of the same footprint mount may not seat, because its 5.23 mm recoil lug can be too wide for the 4.57 mm Weaver slot. Buy the Weaver-cut mount, or fit a Picatinny base first.
OpticHolosun 509T X2Holosun 509T
seats on
RailWeaver rail4.57 mm slot, narrower than Picatinny
Fit readoutBench figures
Fitment
Optic type
enclosed-emitter reflex
Mount
Weaver-compatible Holosun 509T mount
Mount the Holosun 509T X2 on Weaver
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The Holosun 509T X2 is a Holosun 509T optic, so it needs a Holosun 509T mount. On a Weaver base that mount has to be a Weaver-compatible version: Weaver slots are narrower and spaced differently from Picatinny, so a full-width Picatinny recoil lug may not drop in.

If the only Holosun 509T mount you can find is Picatinny-cut, the cleaner fix is to replace the Weaver base with a Picatinny rail, then use the standard Holosun 509T Picatinny mount. Check the mount clamps square before locking it down.

Related fitments

Questions and answers

Fit a Holosun 509T X2 on a Weaver base?

The Holosun 509T X2 reaches a Weaver base through a Weaver-compatible 509T-to-RMR adapter plate on an RMR Picatinny mount. A Picatinny version of the same footprint mount may not seat, because its 5.23 mm recoil lug can be too wide for the 4.57 mm Weaver slot. Buy the Weaver-cut mount, or fit a Picatinny base first.