Just as an asside, we have weapons that were astoundingly similar in principal to a Bolter. IE; they fired small, self propelled rockets with a fractional delayed fuse (they would explode inside the target rather than against it). These were called Gyro-Jets, Designed in the late 70's i think, and came in a pistol and rifle form, both of which were capable of semi-automatic fire. 3 rounds a burst i think, 6 - 12 rounds a clip. Anyway, they never caught on, and now its hard to find ammo for them thats under $12k a round.
As for Lasguns, the argument seems to depend entirely on wether they Las means Laser, as it does in the Dune universe, or if its an acronym for something. The fluff and descriptions in Codex's seems to indicate it is, indeed, a Laser, which means the DOW versions would be more accurate, though even those have their problems.