# Sig Sauer M400 5.56 NATO 16in Black

**Brand:** SIG Sauer
**Category:** AR Style Rifles
**Caliber:** 5.56 NATO

## Specifications

- **Caliber:** 5.56 NATO
- **Barrel Length:** 16"
- **UPC:** 798681726202
- **SKU:** UCE3nP81q

## Description

The Sig Sauer M400 is an AR-style semi-automatic rifle chambered in 5.56 NATO with a 16-inch barrel. It ships with a 30-round magazine and a 6-position Magpul SL-K stock. The Tread V2 variant includes an M-LOK handguard and a stainless steel barrel with the ROMEO5 Gen II compact red-dot sight included.

### Key Specifications
- **Brand**: Sig Sauer
- **Model**: M400
- **Caliber**: 5.56 NATO
- **Action**: Semi Auto
- **Barrel Length**: 16 in
- **Color/Finish**: Black

### Detailed Features
- 16-inch stainless steel barrel
- M-LOK handguard for accessory mounting
- 6-position Magpul SL-K collapsible stock
- ROMEO5 Gen II compact sight included with Tread V2 package
- 30-round magazine included

## Frequently Asked Questions

**Q: What caliber is the Sig Sauer M400?**

A: The M400 is chambered in 5.56 NATO.

**Q: Who makes the M400?**

A: The M400 is made by Sig Sauer.

**Q: What type of firearm is the M400?**

A: It is a semi-automatic AR-style rifle.

**Q: What is the barrel length of the Sig Sauer M400?**

A: The M400 has a 16-inch barrel.

**Q: How many rounds does the Sig Sauer M400 hold?**

A: It ships with a 30-round magazine.

**Q: Does the Sig Sauer M400 come with a stock?**

A: The M400 includes a 6-position Magpul SL-K collapsible stock.

**Q: Is the Sig Sauer M400 optic-ready?**

A: The Tread V2 package includes the ROMEO5 Gen II compact red-dot sight.

**Q: Where can I buy the Sig Sauer M400?**

A: Compare current vendor offers on this page.

## What Customers Say

*AI-generated insights from customer reviews*

Owners of the M400 consistently point to the Tread V2 package as strong value, noting that getting a ROMEO5 red-dot bundled in keeps the total cost lower than buying components separately. The M-LOK handguard and Magpul stock combination draws praise for being light and well-fitted out of the box.

Ergonomics get positive marks overall, though a minority of owners say the Magpul SL-K stock feels a bit stiff until it breaks in. The 16-inch barrel length is seen as a practical compromise for home use and range sessions without being unwieldy.

Reliability with standard 5.56 NATO ammunition is generally reported as solid, with typical AR-platform feeding behavior. Some buyers note the trigger is acceptable but is often the first upgrade they make, which is a common sentiment across this price tier.

## Pricing

**2 offers available**

| Vendor | Price |
|--------|-------|
| Impactguns Com | $1079.99 |
| Selwayarmory Com | $1182.49 |

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*Data from [GunsNation](https://gunsnation.com)*