Used by Moshi in Dark Garden Lake.
A prototype rifle created by the Department of Greenfield Projects (DoGP). It is based on a GNDN railgun but manufactured without any GNDN components.
It has a ten-kilometer range and is capable of using DoGP manufactured armor-piercing (AP) darts or basic GNDN darts. The GNDN darts are almost useless for anything outside of close-range combat against lightly armored opponents. The AP darts are capable of penetrating heavy vehicle armor.
While it is powerful, it has a slow rate-of-fire and is cumbersome to use. It is more manageable in carbine mode but at the expense of range and stopping power.
Excerpt from Dark Garden Lake:
“A regrettable task,” Richard said and pulled a rifle off the shelf of greenfield prototypes.
Moshi accepted the weapon and inspected it. In a lot of ways, a GR-6 was an ideal weapon for this mission. It was more reliable than the railgun it was based on, and the custom-built scope integrated with his augmentation, allowing him to make full use of the weapon's ten-kilometer range. For close range work, he could remove the barrel extension to use it as a carbine.
It wasn't a perfect weapon. The rifle was heavy, and the full barrel was over a meter and a half long. Also, the rate of fire in was painfully low–three rounds per second. As a carbine, it was more manageable, but at the expense of range and stopping power. Still, even basic darts would penetrate light armor.