They already have a railgun-ish model in the game, too: it used to be an endgame weapon, back in the 1.x era. My Operative even still wields one.
Hell, there's even a rare loot-drop version that once dropped at level 50 from Ops and Flashpoints that's so rare, TorFashion doesn't even know it exists; it had DPS Trooper stats, and it was called Ruin. They could probably pull that out of the game files, strip the mods out of it, and sell it as-is...and I'd probably buy a few copies.