In today’s competitive shooting world, performance and reliability often come at a premium. But what if I told you that SIG Sauer has a rifle and optic combination that delivers all the must-haves for serious shooters without the price tag that sends your credit card into cardiac arrest? The M400-TREAD RM400-16B-TRD-V2 paired with the ROMEO5XDR GEN II red-dot optic is that combo.
PURPOSE-BUILT VERSATILITY: M400-TREAD RM400-16B-TRD-V2
Let’s start with the rifle. The M400-TREAD has always been known for its reliability and shooter-centric design. But this latest model, the RM400-16BTRD-V2 chambered in 5.56 mm NATO, ups the ante.
Barrel & Gas System
A 16-inch stainless steel barrel offers exceptional corrosion resistance and consistent accuracy. Combine that with a mid-length gas system and you get smoother cycling and reduced recoil. Whether you’re hammering through a stage or engaging steel at distance, this barrel and gas pairing keeps you on target and in control.
Trigger
SIG’s Matchlite Duo two-stage trigger is a standout here. Clean, predictable and crisp, it allows you to break shots with surgical precision. The flat-faced design feels familiar for serious rifle shooters used to refined triggers, and it gives consistent feedback under stress.
Handguard & Ergonomics
The M400-TREAD’s enhanced M-LOK free-floating handguard is lightweight and rigid, giving shooters a stable platform and easy accessory mounting. Throw on a handstop, light or foregrip with ease and get the exact configuration you want.
Ambidextrous Controls & QD
With an ambidextrous safety and magazine release, this rifle is ready for any shooter, right- or left-handed. It also includes an integrated QD mount on the lower receiver—ideal for sling transitions during Two-Gun and Multi-Gun stages.
Stock & Fit
The Magpul SL-K telescoping stock provides a comfortable, compact profile. It’s adjustable for length of pull and slim enough to streamline your movement through barricades and ports.
Muzzle Device
The SIG Sauer three-prong flash hider rounds out the package by reducing flash signature without affecting balance or adding unnecessary weight. This is a rifle that doesn’t need aftermarket upgrades to be competition ready. It ships as a capable platform that delivers reliable performance out of the box.
SPECIFICATIONS: SIG SAUER M400-TREAD RM400-16B-TRD-V2
- Caliber: 5.56 mm NATO
- Barrel: 16-inch stainless steel; 1:8-inch twist
- Gas System: Mid-length direct impingement
- Muzzle Device: SIG Sauer three-prong flash hider
- Trigger: Matchlite Duo two-stage
- Handguard: TREAD enhanced M-LOK handguard
- Stock: Six-position Magpul SL-K
- Safety & Magazine Release: Both ambidextrous
- Optics Ready: Yes
- Price: Expect to pay between $800-$1,000
COMPACT POWERHOUSE OPTIC: ROMEO5XDR GEN II
Now let’s talk about the red dot. SIG’s ROMEO5XDR GEN II is more than just a red dot. It’s a rugged, refined and surprisingly flexible aiming solution.
Reticle Options
The dual-reticle system (two-MOA dot or 65-MOA circle-dot) is a solid set up. For close-in transitions or fast acquisition, the circle-dot offers an intuitive aiming reference. Flip to the two-MOA dot for precision, ideal for tighter shots at distance or zeroing.
Durability & Build
Built from CNC-machined aluminum, the housing is lightweight yet ready for abuse. Plus, the IPX7 waterproof and fogproof rating means it’s going to hold up in any conditions, like rain, cold, heat or mud.
Battery Life & MOTAC
Powered by a single AAA battery, the optic boasts 50,000 hours of runtime. MOTAC (Motion Activated Illumination) means the dot turns on when you pick it up and off when it sits idle, maximizing battery life and convenience.
Brightness & Controls
Top-mounted ambidextrous brightness controls offer 10 daylight settings and two night-vision modes. You can tailor it to match lighting conditions quickly without fumbling.
Mounting
It comes with an integral 1/2-inch hex mount for rock-solid zero retention, and compatibility with standard mounting heights makes it easy to co-witness with irons or backup sights.
SPECIFICATIONS: SIG SAUER ROMEO5XDR GEN II
- Reticle: Dual; two MOA dot, 65-MOA circle-dot
- Magnification: 1x; 20mm aperture
- Housing: CNC aluminum; waterproof (IPX7) and fogproof
- Mount: 1/2-inch hex
- Brightness Controls: Top-mount, ambidextrous; 12 settings (10 daylight, two night-vision)
- Motion Activation: Yes, MOTAC
- Battery: Single AAA; 50,000-hour life
- MSRP: $229.99
PERFECT PAIRING FOR PRACTICAL PERFORMANCE
So, how do these two perform together? In a word: brilliantly.
You’ve got a rifle with a smooth-shooting mid-length gas system, a precision barrel and a competition-grade trigger. Match that with a red dot that’s versatile, reliable and adaptable to any lighting situation, and you’ve got a setup ready for USPSA-style action rifle stages, Multi-Gun, or plain old range days.
Whether you’re transitioning between targets, shooting from unconventional positions or laying down accurate double taps at 75 yards, this combo delivers. It’s lightweight, fast-handling and rock solid in terms of zero and control.
COMPETITION-READY WITHOUT BREAKING THE BANK
Perhaps the biggest appeal here is value. Many factory rifles in this class lack the attention to detail and out-of-the-box readiness that SIG delivers here. Add to that an optic that’s been battle-tested across civilian and professional applications, and you’ve got an elite-level setup without an elite-level price tag.
This is a serious competition rifle setup for under what many people spend just to upgrade their existing platforms. Instead of piecing together a Frankenstein rifle with aftermarket parts and guessing compatibility, SIG has done the work for you. No compromises.
I’ve run a lot of rifles over the years from custom builds to high-dollar boutique brands. The SIG Sauer M400-TREAD RM400-16BTRD-V2 with the ROMEO5XDR GEN II reminds me why I love factory gear done right. It’s fast, intuitive, tough and accurate.
For the action shooter looking to dive into rifle or Two-Gun, or even the everyday range-goer who wants a reliable workhorse, this SIG combo is hard to beat. All the freedom. All the features. None of the compromises.
If you’re looking to compete without compromise or just want a rifle and optic you can depend on, the SIG Sauer M400-TREAD RM400-16B-TRD-V2 paired with the ROMEO5XDR GEN II optic delivers.
Article from the July/August 2025 issue of USPSA’s magazine.
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