The special rifle and the role as sniper in the team are not the only common features between Kurz Weber's Gernsback and Cherudim Gundam actually. Shinichiro Miki (三木眞一郎), the seiyuu of Kurz Weber also voiced for Lockon Stratos, Cherudim Gundam's pilot.
I suppose that's one reason why the photographer didn't choose to put Robot Damashii [Side VF] VF-25G Messiah Valkyrie (Michael's unit) into the picture, even though it's also a sniper unit. ^^
Ryusei Date from "SRW OG Divine Wars" is also voiced by Shinichiro Miki, and the scene from one of the episodes where he uses R-1 to shoot down a cruise missile should qualify him to be in the scene with Gernsback and Cherudim Gundam as shown above. But there's no Robot Damashii version of any SRW mecha yet. ^^;
Robot Damashii [Side AS] M9 Gernsback (Kurz Weber's Unit) will be out this Saturday (January 23rd) at 3,675 Yen (inclusive of tax).
All images are from Robot Damashii Web.