Problem Solver: HK Front Sight Tower 1913 Rail Mount

By Alton P. Chiu

The Heckler & Koch (HK) family of roller-delayed firearms predates practical weapon lights and modular accessory attachments. The large and unwieldy lights of yesteryear were cumbersome and relegated to specialist roles. The advent of LED and high-energy-density lithium batteries enabled AR-15 users to modularly and ergonomically employ weapon lights. MP5 users must resort to dedicated forends, such as the SureFire 328LMF-A, or upgrade to modern handguards featuring 1913, M-LOK, KeyMod and even Spuhr Interface attachment systems. These solutions are either non-modular or costly.

HKParts solves this predicament with a $40 lightweight aluminum 1913 rail mount attaching to the front sight tower (http://www.hkparts.net/shop/pc/Picatinney-Rail-Mount-For-Front-Sight-Tower-91p16672.htm). It ergonomically positions pistol weapon lights, such as the SureFire X300U and Streamlight TLR-1, on an MP5K with ambidextrous activation. However, it requires fitting to function with a PTR 91 and three-lug muzzle devices such as a suppressor.


To install, one positions the mount on the ejection port side of the front sight tower. Its two legs bracket the tower to align the threaded hole on the mount with the handguard hanger. The supplied lock washer and screw secured the mount snugly against the handguard using a 4mm hex key. The installation was quick and effortless.

The mount was designed for HK dimensions and exhibited excellent fit on the MKE Z-5P (an MP5K license-produced in Turkey). However, the front leg of the mount required some fitting for a PTR 91 (a G3 clone produced in South Carolina). The legs served to align the mount with the bore axis and to prevent rotation during installation. As an additional benefit, the author found that the clamping force eliminated play in the U.S.-made handguard. However, the mount prevented a free-floating barrel.

Fitting for Three-Lug

The front leg, as designed, extends too far forward and prevents the installation of three-lug muzzle devices, as one cannot depress the device far enough to rotate into the locked position. This author was unable to mount his Obsidian45 suppressor from Rugged Suppressors, and he attempted to address this by removing front leg material. However, this modification left only a thin...

This article first appeared in Small Arms Review V22N4 (April 2018)
and was posted online on February 23, 2018


Comments have not been generated for this article.