MR556 A4 SBR

The short-barrelled rifle configuration of the MR556 A4 in 5.56×45, with the same short-stroke gas piston operating system as the rest of the MR family.

The distinction from the pistol version: an SBR has a stock, which makes it a regulated NFA item requiring a tax stamp and federal registration. The 11in pistol has the same barrel length without the stock and without the NFA process.

Worth knowing: SBR ownership is restricted in a number of states regardless of federal paperwork. Confirm your state rules before starting the process. The unrestricted option is the 16.5in rifle.

Parts note: MR556 and MR762 share some components — bolt catch sleeves, sear springs, forward assists — but barrels, buffers, gas blocks and magazines are caliber-specific. Browse upper receiver parts and lower receiver parts.

Compare configurations in the MR Series.

Firearms and regulated components are not sold directly on this site. Listings are informational and link to the manufacturer web shop or an authorised dealer; transfers must be completed through an FFL.