I see you have the ability to do some VFX. I'd suggest treating the blue pistols as VFX shots. There's a great book called "The DV Rebel's Guide". There's a chapter where the author filmed his buddy running around San Francisco with a green plastic pistol. He brought the shots into After Effects and color corrects the green to be gray. I grabbed a still from your trailer and tried the same thing:
It's not perfect, but if you don't have access to realistic props, it looks better than blue pistols (unless that's supposed to be a key part to the story). I live in Montana, USA, and we love our guns, so figured I'd submit this to you.
Good luck on the short! Looking forward to seeing it!