>>96366549 (OP)
Most 40K books describe lasguns in a nearly consistent, much better way than the games, with probably the best portrayal being in the gaunts ghosts novels.
I believe in these the beam is described as continuous and pretty bright/solid looking. I imagine it pure white, but thats just me. The sound of a lasgun is a sharp crack, substantial and satisfying but in a way underwhelming and not quite what you expect, a description which echoes the quality of real gunfire, though las fire is rarely described as particularly loud like real gunfire is. So I think of it as something more sharp, brittle, and cracking than real gunfire, a breaking sort of slapping sound, maybe not so loud, but in quality sharing that vaguely "underwhelming" quality of overheard gunfire.
The more distinctive characteristic is that two different things can happen when it hits a target, that I divide into the categories of a pierce or a splash, or sometimes a more complicated combination of the two.
Sometimes a las round will burn a narrow hole clear through a target, like a clean bullet hole but burned, carrying on the hit things behind it. Or more rarely burrow like this for a while but not exit, but you're still dealing with the same kind of bullet-like circumference burned channel
Often, however, if they lack the power to slice clean through something, you'll get a splash where the end of the white span that forms the round explodes in a sizeable, roundish flash, blasting a crater out of the target, whether a crater of flesh, a big gouge out of a wall, whatever. If the round for whatever reason does not slice straight through, the energy usually dissipates outwards in a way that can be far more damaging, still having a burning effect on the whole impacted area. This also allows them to blow off limbs.
Las rounds can also ricochet, often lose some energy in doing so in the form of a partial splash at the point of initial impact, but will carry on and behave as normal afterwards
