Burris FastFire 3 Footprint: What Fits, What Doesn't, and How to Mount It
The Burris FastFire 3 uses the Docter/Noblex mounting footprint — two screws plus locating sockets on the underside of the sight. Any plate, mount, or milled slide cut for Docter, Noblex, Vortex Venom, or Vortex Viper accepts a FastFire 3, and the FastFire 2 and FastFire 4 share the same pattern. It is not compatible with Trijicon RMR, Shield RMSc, or Leupold DeltaPoint Pro cuts without an adapter plate.
The FastFire 3 is one of the most popular budget reflex sights ever made, which means an enormous number of people eventually ask the same question: what actually fits this thing? Footprint information is scattered across retailer Q&As and decade-old forum threads, so here’s the complete answer in one place.
The Footprint: Docter/Noblex
The FastFire 3 uses the Docter/Noblex standard — named for Docter Optics, the German company (later acquired by Noblex) whose early pistol red dot set the pattern. It’s one of the four big mini-red-dot footprint families, alongside Trijicon RMR, Shield RMSc, and Leupold DeltaPoint Pro.
Mechanically, the sight is held by two screws, with locating sockets on the underside of the sight that mate with posts on the mount or plate to take recoil shear off the screws. If you need exact dimensions for machining, use a proper spec drawing — the Optics Trade footprint database publishes measured drawings — not numbers from a forum post.
Because the industry never standardized naming, the same pattern gets sold under several labels. These all mean the same footprint:
- Docter / Noblex
- Burris FastFire
- Vortex Venom / Viper
- “Docter cut”
Optics That Share the FastFire 3 Footprint
If a mount or slide cut takes one of these, it takes any of them (per the Optics Trade footprint database):
| Brand | Models on this footprint |
|---|---|
| Burris | FastFire 2, FastFire 3, FastFire 4 (NOT the FastFire C — RMSc — or FastFire E — ACRO; family comparison here) |
| Vortex | Venom, Viper |
| Docter/Noblex | Sight C, Sight 3, Sight 2 Plus, QUICKsight |
| Leica | Tempus, Tempus 2 |
| Meopta | MeoSight IV |
| Athlon | Midas TSR1 |
| Sightmark | Mini Shot M-Spec, Mini Shot Pro Spec |
| Delta Optical | MiniDot series |
| Others | UTG OP3 Micro, Vector Optics Frenzy, US Optics DRS 2.0, ADE RD3 series |
What Does NOT Fit
The other three major footprint families are not interchangeable with the FastFire 3:
- Trijicon RMR (also used by Holosun 507C/407C and many others)
- Shield RMSc (the slimline/K-footprint family, including Holosun 407K/507K)
- Leupold DeltaPoint Pro
Adapter plates exist in every direction — companies like EGW machine Docter-pattern plates for most optic-ready slides — but every adapter adds a few millimeters of height. On a pistol that can push the dot above suppressor-height irons; on a rifle it changes your cheek weld. Direct-fit is always the cleaner answer.
Mounting by Platform
Optic-ready pistols. Most factory optic-cut systems (Glock MOS, S&W CORE, and similar plate kits) include or sell a plate for this footprint — look for “Docter,” “Noblex,” “FastFire,” or “Venom” in the plate’s compatibility list. The name varies; the pattern is the same.
AR-15s and carbines. Burris’s own AR-F3 mount puts a FastFire at co-witness height on a flattop — that combination is sold as the “AR FastFire 3.” One warning from the compatibility notes above: the AR-F3’s protective housing is shaped around the FastFire body, so same-footprint-but-fatter optics like the Venom don’t fit inside it.
Shotguns. Burris’s Speed Bead system mounts a FastFire between the receiver and stock, putting the dot in line with a shotgun’s natural point of aim — one of the more clever uses of this footprint.
Anything with a rail. The FastFire 3 is sold with or without a Picatinny riser mount. If you’re buying the sight to move between guns, the with-mount SKU is the flexible choice.
One Buying Tip
When reusing a plate or mount with a different same-footprint optic, check screw length before torquing down. Sight bodies differ in thickness across brands, and a screw that bottoms out — or one thread short — is how footprint-compatible setups still fail. Blue threadlocker, correct length, manufacturer torque spec.
Where That Leaves You
Burris FastFire 3 (3 MOA, with Picatinny mount)
The with-mount SKU is the flexible buy — run it on the rail today, move it to a Docter-cut pistol plate later. Same sight either way.
Check Price on Amazon →Docter-pattern adapter plates (EGW and similar)
If your slide or mount is cut for a different footprint, a machined adapter plate bridges it — just remember every plate adds height. Match the plate to your exact slide cut and the Docter/FastFire pattern on top.
Frequently Asked Questions
What footprint does the Burris FastFire 3 use?
The Docter/Noblex footprint (often just called the 'FastFire footprint' or 'Venom footprint' — they're the same standard). Mounts and plates labeled for any of those names fit the FastFire 3.
Is the FastFire 3 compatible with RMR cuts?
No. The Trijicon RMR pattern is a different standard with different screw spacing and recoil-boss geometry. Mounting a FastFire 3 on an RMR-cut slide requires an adapter plate, which adds height — factor that into whether your irons still co-witness.
Do the FastFire 2 and FastFire 4 use the same footprint?
The open-emitter FastFire 2, 3, and 4 all share the Docter/Noblex pattern, so plates and mounts interchange among those three. Two newer family members break from it: the micro-sized FastFire C uses the Shield RMSc footprint, and the enclosed FastFire E uses the Aimpoint ACRO footprint.
Will a Vortex Venom fit a FastFire 3 mount?
On flat plates and standard mounts, yes — same footprint. The catch is enclosed or form-fitted FastFire mounts like the Burris AR-F3: the Venom's body is slightly larger than the FastFire 3's, so it won't drop into housings shaped around the Burris sight.