This may be a generic gun, but I think I found a match.

 

I gave the single Brainstorm High-Energy Photon Pulse Cannon from the lot to Titans Return Kup, who needed a good gun.



Power of the Primes Voyager Grimlock got the ArtTek Rex Blaster Stunner Lasers.



Shattered Glass Blaster got the small purple DJ Rockblast gun, aka Tractor Beam Electron Gun.

 

Isn't # 1 (the white gun) G2 Blast-Off's?

Edit: It helps if I read the thread fully!

 

RiD Shuttler and G2 Blastoff both have white guns. So you are right.

 

Just for fun here is Combiner Wars Dragstrip with Renderform's Gravito Gun from the lot.

 

Found a low cost loose Skyfall with no weapons for the Empyrean rifle.