M400 Tread
- Category
- Carbine
- Barrel
- 406 mm
- Weight, empty
- 3.17 kg
- Introduced
- 2018
About
What it is, and why it matters
The M400 Tread is a semi-automatic carbine chambered in 5.56x45mm NATO, produced by SIG Sauer since 2018. This American-manufactured firearm reflects the engineering traditions and quality standards of its country of origin, designed to meet the demands of both civilian and professional users in a competitive global marketplace. Featuring a 30-round magazine capacity, this carbine offers generous firepower for duty use and home defense. The 16.0-inch barrel maximizes accuracy potential and ballistic performance, making this an excellent choice for target shooting, competition, or field use. At 3175g (112.0 oz), this is a substantial firearm whose weight contributes to reduced felt recoil and enhanced stability during precision shooting. The aluminum alloy frame achieves a notable weight reduction compared to all-steel construction while maintaining the structural rigidity required for safe, reliable operation. This firearm represents its manufacturer's commitment to delivering a well-engineered, reliable product that serves the needs of discerning shooters seeking quality, accuracy, and dependable performance from a proven platform.
When SIG Sauer unveiled the M400 Tread in October 2018, they positioned it as 'The New Face of Freedom,' a direct nod to the Gadsden flag's revolutionary spirit. The timing was deliberate-launching in an era of increasing political tension around firearms, SIG made a statement that American-made quality and liberty could coexist with affordability, challenging the notion that premium performance required premium pricing.
The M400 Tread is built on SIG Sauer's decade-plus experience with the M400 series, first introduced in 2010. The Tread variant distinguishes itself through its focus on modularity and value without compromising quality. The 1:8 twist rate barrel stabilizes a wider range of bullet weights (55-77 grains) compared to older 1:9 twist barrels, making it more versatile for modern ammunition. The mid-length gas system provides a longer dwell time compared to carbine-length systems, resulting in softer recoil and less wear on internal components. SIG Sauer manufactures the M400 Tread at their Newington, New Hampshire facility. The rifle's thread pattern (1/2-28 TPI) accepts standard muzzle devices. The Tread line has expanded to include pistol variants, predator hunting models, and enhanced V2 versions. Ambidextrous controls include charging handle and safety selector, enhancing usability for left-handed shooters.
Specification
Everything measured
IdentityWhat it is, who built it and when.
- Manufacturer
- SIG Sauer
- Category
- Carbine
- Country
- United States
- Status
- In production
- Produced
- 2018
DimensionsAs issued, without a magazine or an optic.
- Barrel
- 406 mm
- Overall length
- 782 mm
- Weight, empty
- 3.17 kg
- Weight, loaded
- 3.62 kg
ActionHow it cycles, what trips it, and what feeds it.
- Action
- Gas operated direct impingement
- Firing mechanism
- Hammer fired
- Trigger
- Single stage
- Trigger pull
- 29.0 N
- Capacity
- 30
- Magazine
- Detachable box
MaterialsEach swatch is the material itself, not a colour chosen to stand for it.
- Frame
- Aluminum alloy
- Barrel
- Stainless steel
- Stock
- Polymer
- Finish
- Hard coat anodized
BallisticsFrom the service cartridge, not a handload.
- Muzzle velocity
- 905 m/s
- Muzzle energy
- 1640 J
- Effective range
- 500 m
- Maximum range
- 3600 m
Trajectory
What the round does downrange
Solved from the muzzle figures and the bullet. The dashed rule is the effective range on the record, and the crosses are the steps the solver returned.
Features
What it has
What the record lists as fitted, drawn from the catalogue.
Free float handguard
M lok mounting
Ambidextrous controls
Single stage trigger
Mid length gas system
Flat top receiver
Picatinny rail
Magpul stock
Low profile gas block
Standing
How it compares
Each figure against the firearms of the same type and cartridge that record it, or of the same type where that cartridge has too few. Positions are read to the nearest tenth.
| Measurement | This firearm | Median | Position |
|---|---|---|---|
| Empty weightAmong 141 5.56x45mm NATO carbines | 3.17 kg | 2.95 kg | Heavier than about 80% |
| Overall lengthAmong 144 5.56x45mm NATO carbines | 782 mm | 838 mm | Shorter than about 80% |
| Barrel lengthAmong 150 5.56x45mm NATO carbines | 406 mm | 406 mm | Longer than about 70% |
| Magazine capacityAmong 150 5.56x45mm NATO carbines | 30 | 30 | Near the median |
Answers
Questions about the M400 Tread
How much does the M400 Tread weigh?
The M400 Tread weighs 3.17 kg (7.00 lb) empty and 3.62 kg (7.97 lb) loaded.
What caliber is the M400 Tread?
The M400 Tread is chambered in 5.56x45mm NATO.
How many rounds does the M400 Tread hold?
The M400 Tread holds 30 rounds, fed from a detachable box magazine.
How long is the M400 Tread?
The M400 Tread is 782 mm (30.8 in) long overall, with a 406 mm (16.0 in) barrel.
Who makes the M400 Tread?
The M400 Tread is made by SIG Sauer (Germany). It was designed by Eugene Stoner.
When was the M400 Tread introduced?
The M400 Tread was introduced in 2018.
How does the M400 Tread operate?
The M400 Tread uses a gas operated direct impingement action, and its firing mechanism is hammer fired.
Compatibility
Which parts fit this firearm
Studio
Every part that mounts on this, resolved
Not a list the maker typed out: the answer comes from the mounts this firearm exposes and the interface each part needs, so it stays right when either one changes.
- Every part that mounts on any firearm in the catalogue
- Interface standards, platforms and fit overrides
- The same answers through the API and the MCP server
Requires a signed-in GunSpec account on the Studio plan. The answer is computed per part, so it is not part of the public record.
Provenance
What the record holds
Every figure above was taken from one of these pages. The confidence reflects how much of the record came from a page a claim can be checked against.
In service
- United States Law Enforcement
- United States
- Civilian Sport Shooters
- United States
Provenance
Confidence in this record
86%
Stockists
Where to buy
Offers link straight to the shop. GunSpec never takes the order.
No shop has listed this firearm yet
Stock and prices come from the shops themselves. If you sell this firearm, you can list it and it appears here.
List a firearmMCP
Ask an assistant about it
The same record, reached the way a person asks for it rather than the way a program does.
Ask GunSpec
Works with
Point an MCP client at GunSpec and it answers from the catalogue rather than from memory. A free key covers the read tools.
API
The call that returns this record
The same fields, in the same units, from the same endpoint the page reads.
curl --request GET \ --url 'https://api.gunspec.io/v1/firearms/sig-sauer-m400-tread' \ --header 'X-API-Key: your_key'{ "id": "sig-sauer-m400-tread", "name": "M400 Tread", "manufacturer": { "id": "sig-sauer", "name": "SIG Sauer", "countryCode": "DE", "foundedYear": 1985, "website": "https://www.sigsauer.com", "logoUrl": null, "description": null, "status": null, "defunctYear": null, "stateOwned": null, "makesFirearms": null, "parentId": null, "predecessorId": null, "createdAt": "2026-02-11 23:44:40", "updatedAt": "2026-02-18 03:40:48", "version": "944f4088befdcee3b0aa7caf122998351ef3d78abc525a2bdec9df81e65a6b30" }, "category": { "id": "carbine", "name": "Carbine", "description": "Shortened rifles for close-quarters use" }, "country_of_origin": "US", "year_introduced": 2018, "barrel_length_mm": 406, "weight_empty_g": 3175, "action_type": "gas_operated_direct_impingement"}