What we know from the series:
Initially, these weapons showed us a bright blue-white flash at the muzzle when fired, a little deeper blue (at least on my TV) for the Cylons. On occasion however (this happened later in the series), a yellow/white halo was seen to flash around the entire muzzle of the Colonial weapons, followed by a visible red beam of light ala Star Wars. It may be coincidence, or based on some legal clause from the suit with Lucas, but the light beam is only seen when the shooters are engaged against humanoids, and never when engaged with the Cylons.
The actors would occasionally raise the muzzle slightly when shooting, suggesting a moderate recoil to the Colonial weapons.
When a Cylon or a wall is hit, there is usually a bright flash, accompanied by sparks and perhaps secondary explosions, particularly in the case of the Cylons. However, we also see on occasion that, at least where the Cylon�s are concerned, there is very little external damage from the shots. It mostly seems to be scorching and a small amount of material displacement, around what can only be a very small entry wound, as there are cases when it isn�t clearly visible, despite the fact that one or two shots usually took them down. When humans are hit by Cylon weapons, while it seems both painful and damaging, it does not appear to be necessarily immediately incapacitating.
Errant shots sometimes started fires, as in the case of Carilon, but do not seem to against really hard objects like stone and metal.
In ET, we see that the Colonial weapon has a �stun� setting that seems to blanket several individuals per shot.
We know that the Colonial weapon must be recharged after use.
The Colonial weapons belt always has several small brass cylinders attached to it.
What this tells us: I contend that the inclusion of the stun setting establishes that the weapons are multi-functional, and thus, at least in the case of the Colonial weapons, are both a plasma weapon and an EM weapon, usually used as a laser. The core laser weapon is used mostly against objects and heavily armored opponents, while a beam of charged plasma is added (not instead of, but in addition to) against soft targets, and a stun setting modifies the output energies to incapacitate humanoids and creatures with similar physiologies.
Hard Target Mode: I suggest that both the Colonial and Cylon weapons are chemical lasers, firing pulsed coherent light, probably in the high visible � low UV range. The weapon has two sources for its �ammunition�, the battery that provides the energy for all of the supporting functions of the weapon, and the binary chemicals that combine to generate the beam energy. The chemicals might be a number of exotics, but since we are trying to define the details here, I suggest that they are solium and fluorine. For the Colonials, the chemicals are stored in those little brass �recharge� cylinders, and these are fed into the weapon probably through the butt of the grip, and then ejected when empty (much like a standard ammunition clip in a semi-auto pistol). Given the energy potential of tylium, each would probably be good for about 20 shots in laser mode, about half that in the other two modes. Since most warriors carried three, plus one in the weapon, that�s 40 - 80 shots, more than any seen fire-fight ever went.
The energy release is through Q-switching, and the lasers fire over 40,000 pulses per each pull of the trigger, with each pulse being a micro-second in length. With a power of 16.5 watts per pulse, the average delivered energy per shot is roughly 680 KJ (�ergons�). The weapon is relatively short ranged, and is focused via a quantum rod lasing emitter for effectiveness out to 50 meters, although it will still do considerable damage beyond that. Damage is done through direct ablation of the target material as well as subsequent explosive boiling through rapid thermal diffusion (this is what causes the explosion of sparks). In the case of the Cylons, once the armor is penetrated damage is done to the vulnerable power conduits and circuitry.
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