For modern firearm enthusiasts, a positive to the Global War On Terror (GWOT) was that it provided the firearms community many new models, configurations and accessories to clone and research. One of the most popular configurations was the Special Purpose Rifle (SPR) designs that were adopted by SOCOM and then later used in the U.S. Army and United States Marine Corps. Early in GWOT, the Mk. 12 Mod. 0 was in use. I found out about the Mk. 12 Mod. 0 program while co-located with a Special Forces team in Iraq in 2004.

As lessons were learned from the Mk. 12 Mod. 0 SPR and the testing of the 77-grain Mk. 262 bullet, the next iteration of the SPR was being developed. When it was fielded, it was referred to simply as the Mk. 12 Mod. 1 SPR.

The was an additional rifle development by the USMC which was called the Squad Advanced Marksman Rifle or SAM-R. The SAM-R had a similar concept to the Mk. 12 family but had some different parts. The SAM-R rifles were assembled by the USMC Precision Weapons Section of the Weapons Training Battalion at Quantico.

Colt never made a dedicated SPR/SAM-R for the military or civilian market. They did create a small number of SPR type rifles for a law enforcement trial as discussed elsewhere here on the website. The Mk. 12 Mod. 0 and Mod. 1 SPR’s were a conglomeration of parts assembled by Naval Special Warfare Center (NSWC) Crane. They typically used M16A1 lower receivers (to retain full-auto capability) and Colt upper receivers.

When Walther designed the ‘Colt M16 SPR’ they seemed to have combined features from the Mk. 12 Mod. 1 and a spin off weapon design called the SAM-R. From the SAM-R they have the folding front sight/gas block. From the Mod 1 concept they have a railed forearm that is a vague copy of the Knights Armament free-float rail adapter system. The rear sight design that Walther used is replica of the Knights Armament 0 – 300m rear sight that was used for a while in the Special Operations Command SOPMOD program.

Without further delay, let’s look at some detailed photos of the Colt Walther M16 SPR.

The accessory bag includes a gun safety padlock, two hex keys for disassembly and rate of fire adjustment and a wrench for removal of the flash hider.

Although the buttstock looks similar to standard AR/M-16 buttstock, it has a noticeably different feel and weight.

Of note is the absence of rail numbers on the rail system or the upper receiver.

Receiver markings on the right side of the lower receiver are:

US IMPORTER, UMAREX USA, FORT SMITH, AR

On the magazine well is LICENSED TRADEMARK OF NEW COLT HOLDINGS CORP. MADE BY CARL WALTHER, GERMANY

In the image below the absence of the a gas tube coming from the upper receiver into the gas block/front sight is very obvious. The .22LR operating system is direct blow back and doesn’t use any movement of gases from the firing cycle.

As seen below, the flash hider is threaded onto the barrel (which is an insert) and is removed for cleaning and maintenance. The flash hider is of the A1 design with flash ports around the full circumference of the part.

The selector is fire and safe. The positions are 180 degrees from each other.

In the image below are the front and rear receiver pins that hold the top and bottom receiver sections together. Unlike an actual AR/M4/M16 series firearm, these pins are different lengths.

The images below show the 10-round magazine that come with the rifle