The HK MR762 A4 13-inch upper receiver kit, from Heckler & Koch, brings the latest A4 updates to a standalone upper receiver group (brand part no. 51001919). It is the commercial version of the HK417 line, now with a new barrel profile, adjustable gas regulator and handguard. The 13-inch match-grade cold-hammer-forged barrel has a medium contour and concentric 5/8×24 threads for a muzzle device. A continuous Picatinny rail runs between the handguard and the upper receiver for optics and accessories. It suits builders who want a compact 7.62x51mm upper from HK.

Key Specifications

• The barrel is 13 inches, a compact length that keeps the rifle handy.
• The chambering is 7.62x51mm, the full-power cartridge the MR762 line is known for.
• The barrel is cold hammer forged, a match-grade process known for consistent accuracy.
• The barrel profile is medium contour, balancing weight and heat handling.
• The muzzle has concentric 5/8×24 threads, ready for a compatible muzzle device.
• The gas system has an adjustable gas regulator, which lets you tune the action for different loads.
• A continuous Picatinny rail runs between the handguard and the upper, giving a long mounting surface.
• The finish is black anodized, a durable coating for the receiver.
• The kit is a complete standalone upper receiver group, so it comes as a ready-to-install assembly.
• It carries the A4 updates, including the new barrel profile, adjustable gas block and handguard.

Frequently Asked Questions

Is the upper threaded? Yes. The 13-inch barrel has concentric 5/8×24 threads at the muzzle.

Can the gas system be adjusted? Yes. The MR762 A4 upper has an adjustable gas regulator.

What makes it an A4? The A4 update adds a new barrel profile, an adjustable gas block and a new handguard with a continuous Picatinny rail.

Buy the HK MR762 A4 Upper Receiver Kit, 13-Inch Barrel, 5/8×24 Threaded

For a builder who wants an HK upper without the full rifle, the MR762 A4 delivers the match barrel, adjustable gas and rail platform in one assembly. Order it from our Lubbock, Texas gun shop for fast, insured shipping, and look through our other AR-10 uppers too.