SIG SAUER M400 SDI 10-Inch M-LOK Free-Float Handguard – Black 9.9 oz

The SIG SAUER M400 SDI 10" M-LOK Handguard is a genuine factory replacement designed specifically for the SIG M400 SDI X and TREAD platforms, while maintaining full compatibility with standard AR-15 mil-spec builds.

Machined from lightweight aluminum and finished in durable black anodizing, this free-float handguard improves accuracy by eliminating barrel contact during supported or rested shooting. Integrated M-LOK slots along the sides and bottom allow easy mounting of lights, grips, and accessories, while the M1913 Picatinny top rail supports optics and iron sights with a continuous, rigid mounting surface.

Strategic lightening cuts reduce overall weight without sacrificing strength, keeping the rifle balanced and maneuverable. Whether you’re restoring a factory SIG rifle or upgrading a custom AR-15 build, this handguard delivers factory-correct fit, clean aesthetics, and proven performance.

This kit includes the barrel nut, clamps, and installation hardware, making it a complete drop-in solution for compatible rifles.

Key Features & Benefits

• Genuine SIG SAUER factory M400 SDI X handguard

• Free-float design improves accuracy and consistency

• M-LOK slots on sides and bottom for modular accessories

• M1913 Picatinny top rail for optics and sights

• Lightweight aluminum construction with lightening cuts

• Durable black anodized finish

• Complete kit includes barrel nut, clamps, and screws

• Compatible with standard AR-15 mil-spec platforms

Specifications

• Brand: SIG SAUER

• Model Compatibility: SIG M400 SDI, SIG TREAD

• Platform: AR-15 (Mil-Spec)

• Handguard Length: 10 in

• Material: Aluminum

• Finish: Anodized

• Color: Black

• Accessory Rail: M1913 Picatinny (Top)

• Mounting System: M-LOK (Sides & Bottom)

• Free-Float: Yes

• Suppressor Capable: No

• Barrel Nut: SIG M400

• Weight: 9.9 oz (0.62 lb)

Included in the Box

• SIG SAUER M400 SDI 10" Handguard

• Barrel Nut

• Barrel Clamps

• (2) Mounting Screws

• Installation Hardware

Most in-stock items ship within 3 business days.

Special order items are typically processed within 14 business days (excluding weekends and holidays).

Custom items may require additional time depending on production schedules.

If you’d like to receive your order sooner, please select an expedited shipping option at checkout.

Some products ship directly from the manufacturer, and an equivalent carrier or service level will be chosen to match your selected shipping speed.

Shipping delays caused by carriers are outside our control, but we’ll always help track updates.

See our Shipping Policy for details.

Returns are accepted within 14 days for items that are unused, unopened, and in original packaging with no damage.

A restocking fee applies, but it may be partially waived if store credit is selected instead of a refund to the original payment method.

Custom builds, sale items, and hazardous goods are final sale.

Warranty Coverage: Manufacturer warranties apply to all standard products. Any defects, malfunctions, or performance issues are handled directly by the manufacturer per their terms.

HR Tactical Innovations covers a Fitment & Functionality Guarantee on all custom or modified items — if a verified production error occurs, we’ll replace the item.

View our Refund Policy for full details.

We ship worldwide to Canada, Mexico, Europe, Asia, and Oceania, including:

🇨🇭 Switzerland • 🇨🇿 Czechia • 🇩🇪 Germany • 🇩🇰 Denmark • 🇪🇸 Spain • 🇫🇮 Finland • 🇫🇷 France • 🇬🇧 United Kingdom • 🇭🇰 Hong Kong SAR • 🇮🇪 Ireland • 🇮🇹 Italy • 🇯🇵 Japan • 🇰🇷 South Korea • 🇲🇾 Malaysia • 🇳🇱 Netherlands • 🇳🇴 Norway • 🇵🇱 Poland • 🇵🇹 Portugal • 🇸🇪 Sweden • 🇸🇬 Singapore • 🇦🇺 Australia • 🇳🇿 New Zealand • 🇦🇪 UAE and more.

Transit averages 2–4 weeks depending on customs clearance. We are not responsible for customs delays. Reduced transit times are only available through expedited shipping options.

Import duties, VAT, and taxes are not included in your order total and must be paid by the recipient.

If a package is rejected, unclaimed, or returned due to unpaid duties, an incorrect address, or failure to collect, it will be handled under our Refund Policy. Shipping costs are non-refundable in these cases.

Pressurized or restricted items ship ground only where permitted.

Questions? Contact ops@hrtacticalin.com before checkout.