In May of this year, I got the rare opportunity to travel to Heckler & Koch’s headquarters in Ashburn, VA, to take a look at some of the experimental and prototype firearms they have located there in their famous “Grey Room”. It wouldn’t be worth as much for me to just tell you about it and to snap a few foggy cell phone pictures, though, so I brought along Othais of C&Rsenal to help me take high resolution light box photos of these unique and rare firearms.

Previously, we looked at the Heckler & Koch G11K2 caseless ammunition-firing hyperburst rifle, which was cancelled with the fall of the Berlin Wall and the need to reconstruct East Germany. Today we’ll be taking a look at the version used in the US Advanced Combat Rifle program of 1989-1990, which explored then-new technologies that could form the basis for the next great leap in individual weapons for the 1990s. This was the last big hurrah for the G11, and the version of the rifle used for these trials is simply called the “G11 ACR”.

In case you were wondering exactly what the inside of the G11 looks like, too, we also photographed a display model of the rifle’s mechanism, playfully labeled “Jim’s Toy” (I assume the name refers to Jim Schatz, the program manager for the G11 at the time):

If you want to download all of these photos in their full resolution, you can follow this MediaFire link to a zip file containing them.