I have reconciled 'deadly laser' with 'silent' by removing the 'deadly laser' part.
Needle Pistol, 15 points: Encumberment 2, Moving Modifier –2, Re-load 10/45x2 *, Spread *, SFSH 5, Close Combat, 0-6” +2 / 3+3D6, 6-12” +1 / 2+3D6, 12-18” –1 / 1+3D6, 18-24” –3 / 3D6.
Low Power: Spread *, SFSH 1, Close Combat, Low Velocity, 0-6” +2 / 1+3D6, 6-12” +1 / 3D6, 12-18” –1 / 1+2D6, 18-24” –3 / 2D6. Each shot fired on Low Power uses half a normal ammunition point from an ISPP cell.
Ammo 3 points per 10 shot projectile vial, Encumberment .25 per 2, ISPP cell, 45 individual shots, 2 points per 1, Encumberment .25 per 2.
6 points per ISPP (3 cells), Encumberment .5.
A Needle Pistol may be fired when its projectile vial is empty/not loaded, or set to fire without launching a projectile.
If a target takes any damage from a Needle Pistol while it is loaded with a full or partially full projectile vial, and set to fire projectiles, they are treated as being doped as per the rules for Dart & Bolt Launchers.
* Re-load 10/45x2; after 10 shots, the weapon must be re-loaded with another projectile vial as 2 Additional actions. After 45 shots have been made, the ISPP cell must be re-loaded as 2 Additional actions.
Notes: A weapon of convoluted design and dubious tactical utility, it resembles a bulky las-pistol. The needle pistol is most commonly used as a less-lethal method of incapacitating a target, and conversely as a discreet tool of assassination. It may be fired with comparable performance to a las-pistol, or it may be switched to fire a crystallised sliver of fast-acting toxin or sedative into a target, propelled relatively silently by laser ablation acting on the base of the crystal dart, the reaction contained within the barrel, and muffled at the muzzle by a sound suppressor. The solid projectile is propelled at a sub-sonic velocity, but still has more than enough energy to kill a human target with a carelessly, or carefully, placed shot.
So when firing needles, the laser is used to propel the projectile, but never actually leaves the barrel.
With a plasma weapon, I think the amount of mass in the projectile is going to be closely related to the amount of energy it has, or how hard it hits. So a plasma weapon that hits hard is going to be launching more mass than a weaker weapon.
If a plasma weapon has a practical range and the destructive effect of a 500 gram HEAT warhead, I think the mass of the plasma it is shooting is more likely to be significant, rather than insignificant.
A note on super-hot-ness.
As I understand it, to inflict damage, simply being really hot isn't enough. The heat has to be sustained and transferred, and I don't think something with negligible mass could do a very good job of sustaining or transferring heat.
I've heard of experiments showing x-rays to be visible to the human eye, under low-light conditions. So I think it's likely that an intense, deadly, focussed beam of x-rays would be even more visible.
The exact calibration and output and all the other technical stuff that would result in a laser weapon with performance that would closely resemble that of an assault rifle (a las-gun), is beyond my knowledge as well. So I'm operating on the assumption that if it has effects comparable to an assault rifle, then it may well have side-effects comparable to an assault rifle as well. I think it's a safer assumption to make, than assuming that a laser rifle or plasma gun wouldn't have at least some associated side-effects.
So yeah, I think we agree. Side-effects are very likely.
As an explanation of my methodology, I'm holding things to this degree of reason and accountability simply because this is my work. There is no shortage of supposed Science-Fiction creators going about their business (and getting paid for it) seemingly oblivious to the wealth of human knowledge accumulated throughout recorded history, completely ignorant to the known facts of the real world - which I complain about endlessly. And simply put, I don't want to be a hypocrite.
So even when dealing with someone else's work, like the 40K universe, with its well-known flagrant disregard for the laws of physics, I have to try and meet at least half way when reconciling the established material with reason and accountability.
_________________Warhammer 40,000 5th edition
The least worst rules for 40K.
The purpose of writing is to inflate weak ideas, obscure poor reasoning, and inhibit clarity.
With a little practice, writing can be an intimidating and impenetrable fog, behind which halftruths and untruths can frolic and procreate unmolested.