SIG TREAD Rifle: Tailored Upgrades for Under $1000

SIG Sauer’s M400 TREAD is moderately priced premium entry-level rifle accompanied by a full-line of TREAD branded accessories giving the consumer the freedom to tailor the rifle to their application and budget.

The M400 has ambidextrous controls: safety selector and magazine release button with an oversized bolt latch.use.

Built on an M400 upper and lower with ambidextrous controls: safety selector and magazine release button. The bolt latch is oversized for ease of use. The TREAD has an optics ready free-floating M-LOK hand guard covering a 5.56 NATO 16” stainless steel barrel.  The unconventional hand guard design has 12’o-clock M-Lok slots in-place of a Picatinny rail. With the full-length 15-inch non-skeletonized hand guard the Tread weighs 7 pounds.

The three prong flash hider is effective and has a cool retro look. It is suppressor-ready with a tight match to SIG’s cans. A single-stage polished/hard-coat trigger, a Magpul™ SL-K 6 position telescoping stock, a mid-length gas system complete the build.

The M400 TREAD has a unique mid-length gas system. The SIG micro-light gas block is the smallest I have ever seen. It allows for very low profile handguards. The factory-installed, aluminum, free-floating M-LOK™ handguards can be removed with two hex screws to change out to TREAD accessory options.

SIG’s amazing Micro-Light Gas Block

The difference between SIG’s TREAD and the competition is not just the excellent M400 chassis. The TREAD is a complete system of OEM upgrade parts that assure compatibility making building your custom rifle simple and affordable.

Tread branded accessories

New rifle owners can select any of the yellow and white TREAD branded boxes at their local dealer or the SIG website and be sure that the parts will fit and run. No more worrying about delta rings or barrel nuts, thread patterns or accessory rail designs.

The TREAD branded accessories include an M-LOK handguard with lightening cuts to reduce weight (available in 13” and 15” lengths), a 3 chamber compensator, an ambidextrous charging handle made of aircraft-grade aluminum and a dual roll pin design, a ROMEO5 optic featuring a 2MOA dot with ten illumination settings, MOTAC, and 50k battery life. They also include a flip-up front, rear iron sights that are easy to install, adjustable, and deploy quickly, an M-LOK front sight adapter with co-witness height made of lightweight aluminum, multiple configurations of M-LOK grip kits made of high strength polymer, and a factory upgraded flat blade, single-stage trigger.

I had the opportunity to travel to New Hampshire to visit the SIG Sauer factory. Their production technology is highly automated with multiple quality checks. I got to walk the production floor and see every step of the process from machining to assembly. Trained professionals assemble guns and reject any component which isn’t perfect, but that is only half the story.

One of the SIG Sauer factory floors in New Hampshire.

There is a quality plan for each part which dictates how many parts from each lot are checked at special robot laser verification stations which check every angle of a part. These check stations are connected to each of the automated CMC machines and automatically update the instructions to the machines, in real time.

Problems are anticipated and avoided. This reduces bad parts, keeps them out of the supply chain and cuts costs so SIG can make better and less expensive guns.

They test fire every gun on a 100-yard range in the middle of the factory. SIG also makes the ammunition and precisely controls each step of the process.

I was invited to the SIG Academy for the TREAD launch event. Shooting the M400 TREAD for a day—under strict the tutelage of the SIG Academy staff—meant putting thousands of rounds down range.

We started out in the morning with the M400 TREAD in its out-of-the-box configuration with a Romeo 5 sight.

The author in the High Ready position with the TREAD on the line at the SIG Academy.

The TREAD-branded Romeo5 (1x20mm red dot) features 8 daylight and two night vision power settings.SIG’s advanced MOTAC motion-sensing power function automatically powers on when it is picked up and shuts off when there is no movement. Battery life? 50,000-hour run time on a single CR2032 cell. All for an MSRP of $149.

Stock, the TREAD features a mid-length gas system, 1:8-inch twist stainless steel barrel, a very low profile gas block, an aluminum handguard with M-LOK slots, a single-stage mil-spec trigger, ambidextrous controls, suppressor-ready 3 prong flash hider, QD sling sockets, and a Magpul MOE SL-K stock.

The stock trigger has SIG’s diamond-like coating and pulls at about 7.5 pounds. I prefer something a little lighter but the break was crisp with no creep.

Barricade shooting on the urban facades at the SIG Academy

During lunch, SIG armorers swapped the basic parts with TREAD branded upgrades.

SIG Armorers changing TREAD parts over.

I kept the base handguard, which I like, and opted for an upgraded flat blade, single stage 4.5 pound trigger and an M-LOK Hand-Stop Kit. The TREAD works fine without upgrades but you can always refine the parts for your application.

Shooting the Jungle Run at the SIG Academy

I shot 700+ rounds of SIG Elite 55gr FMJ ammunition at paper and steel targets out to 300 yards. We took brand new guns out of the boxes and ran them hard shooting magazine after magazine in drills.

Zeroing unsupported prone at 50 yards with a Romeo5 red dot produced groups just over one inch for me. We shot steel targets from various positions out to 300 yards with universal success. I am sure this rifle is capable of 1 MOA performance with the right ammunition and magnified optic.

I found the controls on the M400 TREAD ergonomic and easy to use right and left handed. The rifle is a joy to shoot in any position and I found no negatives.

Moving to the tower at the end of the jungle run.

We worked up to multiple targets and shooting several scenarios in the woods, around cars and barricades. The guns worked perfectly as expected. I didn’t have a malfunction and didn’t see one anywhere on the line all day.

M400 TREAD Rifle Specs:

OPERATING SYSTEM: Direct Impingement
OVERALL LENGTH: 30.8 in (782 mm)
OVERALL WIDTH: 2.5 in (64 mm)
HEIGHT: 7.5 in (191 mm)
BARREL LENGTH: 16 in (406 mm)
WEIGHT: 7 lbs (3.2 kg)
MAG TYPE: Standard AR-15


A fully accessorized Tread M400

MSRP: $951.00
Expected Street Price: Around $

SIG display case with the Tread and all of the accessories

M400 TREAD Branded Accessories Specs (all prices MSRP):

  • M-LOK Handguard 15”: $149.00
  • M-LOK Handguard 13”: $149.00
  • ROMEO 5 Optic: $149.00
  • Adjustable Flip-Up Sights: $149.00
  • Single-Stage Trigger: $119.99
  • Ambidextrous Charging Handle: $49.00
  • 3 Chamber Compensator: $49.00
  • M-LOK Front Sight Adapter: $29.00
  • M-LOK Hand-Stop Kit: $29.00
  • M-LOK Vertical Grip Kit: $29.00

The M400 TREAD and TREAD accessories are available in retail stores. The full-line of TREAD rifle accessories and TREAD branded apparel can also be purchased at

SIG set out to build moderately priced premium rifle packed with innovation and flexibility which does not sacrifice quality. The M400 TREAD and branded accessories do not disappoint.

This is a perfect way for shooters to enter the AR market without breaking the bank and getting the gun they want. If the budget doesn’t allow the complete system desired, the buyer can upgrade over time.

The M400 is a proven platform and this new model has all the quality and value shooters have come to expect from a SIG.

Images provided by SIG Sauer and Matt Stagliano of Firelance media. For more information on the SIG Tread visit SIG by clicking here.

***Shop GunsAmerica for your next SIG Sauer***

About the author: Mark Miller is a former Customs Agent and a Green Beret who served in Afghanistan and a number of other live fire locations. A student of firearms and shooting, he is an FFL and a SOT. The guiding philosophy of his life is that terrain and situation dictate tactics and the enemy always gets a vote on any plan.

{ 9 comments… add one }
  • Lon November 20, 2018, 7:16 am

    Too bad handguard length isn’t optional I’d prefer the 13″. Heck, I’d prefer Magpul SL handguard, a front sight base, and knock off about $100 off msrp.

  • Michael Light November 12, 2018, 3:02 pm

    Can I order the M400 TREAD straight from you built the way I want it?

    Michael Light

  • Scotty Gunn November 5, 2018, 7:04 pm

    Ar’s are down to about Three hundred to three fifty now. Unless this has a match trigger and match barrel, I’ll pass.

    • Mike V November 6, 2018, 12:47 am

      The super cheap AR builds are down to around 300-400…

      Major manufacturer ARs arent. This is wholly in line with its competitors…that aren’t made with plum crazy lowers…

      Is this worth the list price? Maybe not.

      If you can build your own competently, you can produce better results for less $$

      Most people don’t want to get into that and having a factory built system super easy to modify is worth the peace of mind and $$ to those people.

  • Bad Penguin November 5, 2018, 7:52 am

    With a 1:8 twist why were you shooting 55 gr ammo? It works but for accuracy for a twist that slow you’d need 72 gr ammo.

    • Johnny Raygun November 6, 2018, 10:07 am

      The original design was a slow 1:14 twist, production came with a 1:12. These twist rates were specific to 55 grain ball ammo. When heavier bullets like the 62 grain penetration appeared,(Green tip) , the 1:9 twist was the next big change. Now with 70+Gr bullets 1:7 is most common. Faster twist rates can handle heavier bullets and still shoot accurately with 55gr bullets.

  • Bad Penguin November 5, 2018, 7:47 am

    Changing away from a milspec trigger is the single best thing you can do to increase your shooting accuracy. It would be worth the upgrade.

  • Mike Larsen November 5, 2018, 3:55 am

    Sigh. M-LOK. Will they be offering Keymod as an option in the future?

    • Jamie November 5, 2018, 7:51 am

      Keymod is all but dead. It’s been proven over and over that mlok is just better. Which sucks for us since I have a couple dick mod rails too.

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