Can you run a Burris FastFire C on a 20 mm RIS or RIS II airsoft rail? Yes, through its RMSc-footprint Picatinny mount. The Picatinny-pattern fit and the clone-rail tolerance to check.

Updated 05 September 2026.

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

Fit a Burris FastFire C on an airsoft RIS rail

Name: Fit a Burris FastFire C on an airsoft RIS rail: published specification
Creator: Scope Mount Finder
License: https://creativecommons.org/licenses/by/4.0/

The Burris FastFire C is a Shield RMSc optic. Here is how it clamps a 20 mm airsoft RIS rail and the one thing to check on a clone rail.

Direct fitThe Burris FastFire C runs on a 20 mm RIS or RIS II airsoft rail through its RMSc-footprint Picatinny mount, exactly as on a live-fire Picatinny rail. On a good replica rail it clamps square; on a cheap clone rail, seat it dry first and confirm it locks, because clone rails can sit out of Picatinny spec.

OpticBurris FastFire CShield RMSc

seats on

RailAirsoft 20 mm RIS / RIS II railPicatinny-pattern; check clone tolerance

Fit readoutBench figures

Fitment

Optic type

open-emitter reflex

Mount

RMSc-footprint Picatinny mount

Dot size

6 MOA

Mount the Burris FastFire C on airsoft

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A 20 mm RIS or RIS II airsoft rail is built to the Picatinny pattern, so the RMSc-footprint Picatinny mount that carries the Burris FastFire C on a live-fire rail clamps the replica rail the same way. The footprint choice does not change: it is still a Shield RMSc optic on a Shield RMSc mount.

The variable on airsoft is the rail, not the sight. A quality RIS or RIS II rail holds Picatinny slot width and pitch, but a budget clone rail can run slightly narrow or wide. Seat the mount dry, check the Burris FastFire C sits square, and confirm the clamp locks before a skirmish so recoil-free cycling does not shake it loose.

Related fitments

›Burris FastFire C on a Picatinny railthe live-fire case
›Burris FastFire C footprint and mountthe optic
›Airsoft 20 mm RIS / RIS II railthe rail
›Shield RMSc footprintthe pattern

Questions and answers

Fit a Burris FastFire C on an airsoft RIS rail?

The Burris FastFire C runs on a 20 mm RIS or RIS II airsoft rail through its RMSc-footprint Picatinny mount, exactly as on a live-fire Picatinny rail. On a good replica rail it clamps square; on a cheap clone rail, seat it dry first and confirm it locks, because clone rails can sit out of Picatinny spec.