Gear Guy / Builds / HK416 Spec-Ops

Build file · HK416 platform

HK416
Spec-Ops

An MR556 A4 receiver set with an 11″ HK416 A5 piston barrel and slim-line handguard, an SB Tactical brace, a SIG SURG556 over a Taper-Lok brake, an EOTech EXPS3-2 and G33 on Unity FAST risers with the magnifier on the FTC arm, a Wilcox RAID-X, and a SureFire M300C run from a pressure pad. Configured entirely in Gear Guy — this page is the build’s actual parts file.

11″Barrel · piston
19 partsfitted on the bench
$9,698Parts listed below
NFAsuppressor · brace, see below
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The HK416 Spec-Ops configuration rendered on Gear Guy's bench

Captured from the app · this exact configuration

Parts file

What’s on this rifle.

Straight from the app’s shared build page — including which parts ship to your door, which need a licensed dealer, and which live under the NFA.

BUILD FILE · HK416 SPEC-OPSHK416 / MR556 · 11″ · 5.56
PartFulfillmentPrice
HK MR556 A4 Upper Receiver KitHeckler & Koch · upper_receiver FFL transfer required $1,939
HK MR556 A4 Complete Lower ReceiverHeckler & Koch · lower_receiver FFL transfer required Price TBD
HK416 A5 11in Barrel (Adjustable Gas Piston)Heckler & Koch · barrel Ships to your door In the upper kit
HK416 A5 Slim-Line Handguard 10"Heckler & Koch · handguard Ships to your door In the upper kit
SB Tactical SBA3 Pistol BraceSB Tactical · stock Ships to your door $130
HK416/MR556 Pistol Grip V2Heckler & Koch · grip Ships to your door $52
SIG SRD556-QD Taper-Lok Muzzle Brake (1/2x28)SIG · muzzle Ships to your door Price TBD
SIG SURG556SIG Sauer · suppressor NFA item · ATF registration $1,899
EOTech EXPS3-2 (FAST 2.26" riser)EOTech · optic Ships to your door $949
EOTech G33 3x Magnifier (FAST FTC riser)EOTech · magnifier Ships to your door $559
Magpul PMAG 30 Gen M3 Window (5.56)Magpul · magazine Ships to your door $16
SureFire M300C Scout LightSureFire · light Ships to your door $299
Wilcox RAID-XWilcox Industries · laser Verify export & local law $3,571
SureFire SR-D-IT Dual Pressure Pad (Light + ATPIAL Laser)SureFire · switch Verify export & local law $139
Magpul M-LOK Hand Stop KitMagpul · foregrip Ships to your door $25
Mil-Spec Single-Stage TriggerVarious · trigger Ships to your door Price TBD
Mil-Spec Charging HandleVarious · charging_handle Ships to your door $15
Mil-Spec BCG (MPI/HPT)Various · bcg Ships to your door $90
Carbine Buffer & Spring KitVarious · buffer Ships to your door $15
19 parts · 3 unpriced · 2 included in the upper kit · captured September 2026 PARTS LISTED $9,698

A braced pistol, a registered can — read this part

This configuration has an 11-inch barrel and a pistol brace, not a stock. The suppressor is an NFA item and requires ATF registration. As of January 1, 2026 the federal tax is $0, but registration is still required. Whether a braced pistol like this one is treated as a pistol or as a short-barreled rifle under federal law has moved through rulemaking and litigation more than once; do not rely on this page for its current status — verify current ATF guidance before configuring a real firearm. Gear Guy’s NFA sheet flags the question; it never answers it for you.

This is general information, not legal advice. Federal rules only — your state may differ. Rules change; verify current ATF guidance before configuring a real firearm. Learn more at atf.gov.

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