This is the gun that Shepard goes for as soon as he falls out of the ‘portal’ into the world of Terra Nova.
It looks both a little rough (air bubbles in the casting) and clearly has solid / filled-in barrels.
However, other pistols, shown in close-ups or in still photos, also appear to have a few small bubbles and filled barrels.
Due to the apparent roughness of this cast, I’m guessing that this may be a solid rubber ‘stunt’ pistol.
‘Heros’ probably are cast resin that is better cleaned-up and painted, and maybe weathered.