Article first appeared at Shooting Illustrated.

It turns out both good—and rare—things are worth waiting for. Case in point: Back in 2009, I began the process of transforming a SIG Sauer P556 pistol into an NFA-based short-barreled semi-auto rifle project with the goal of giving said firearm a face-lift so it resembled the iconic SIG SG 552 Commando Carbine.

The SIG SG 552 Commando is a carbine variant of the SIG SG 550, a battle rifle designed in the 1980s and built from 1986 until just a few years ago. The rifle is based on the earlier SIG SG 540, and both used a gas-actuated long-stroke piston-driven system much like those used on the iconic AK series of rifles. However, the 550 and later variants featured an adjustable gas valve with two settings: one for normal operation and another to deal with excess fouling or icing.

Despite accumulating most of the necessary furniture and components along the way, on an aesthetic and technical level, the version I created wasn’t as precise as it could have been in that my rifle’s lower receiver was designed to accept STANAG magazines, not the original proprietary Swiss magazines. To compound matters, SIG Sauer ceased production of its line of AK-based rifles a few years ago.

Fortunately, Lady Luck (and people within the firearm industry) occasionally learn of such projects and, every now and then, have the parts one needs to bring a long-term project to a well-deserved close.

The purchase of a second lower receiver and four of the original translucent Swiss magazines makes this rifle even closer in appearance to its shorter-barreled Swiss cousin.