The Metal Blaster is a unique laser rifle that fires nine laser beams while expending only one microfusion cell. Everett explains that it was created by a man from The Pitt using parts he found lying around The Mill, including a series of prisms that split the beam. Everett came into possession of the rifle by looting the man's corpse in the Mill.
It is repaired with the standard AER9 laser rifle or the Wazer Wifle.
It deals considerably more damage than the standard AER9 laser rifle.
It lacks the precision of a standard laser rifle, making it less effective for long-range attacks.
The spread remains consistently tight when firing outside of V.A.T.S. mode; however, when firing within V.A.T.S. mode, a registered "miss" will make the spread much wider than it is outside of V.A.T.S. mode (though some beams may still connect with the target, doing slight damage). Because of this and the single critical/shot limitation of V.A.T.S., this weapon is far more effective outside of V.A.T.S.
The 55 base damage is split between each of the nine beams, but outside of V.A.T.S. each beam can cause a separate Critical Hit, doing +27 damage per beam. Furthermore, a sneak attack critical automatically scores critical hits with all beams. The combination of a sneak attack and the Better Criticals perk will result in 839 total damage.
Tri-beam laser rifle - The tri-beam laser rifle is a variant of the AER9 that fires three high-powered beams per shot - similar to the Metal Blaster - though it does require three microfusion cells every time the trigger is pulled. This weapon is not unique and is dropped by super mutant overlords but is not repairable with anything but other tri-beam laser rifles. It was first made available in Broken Steel.
The following is based on Fallout 3 cut content and has not been confirmed by canon sources.
A "demo" version of the laser rifle is included in Fallout 3, presumably left from the game's E3 demo. It does one point less damage per shot and less than half the critical damage than the standard variant, but has a much higher critical chance percentage. It is not used anywhere in the game and is only accessible through the use of console commands.
End of information based on Fallout 3 cut content.
The Metal Blaster's laser beams won't set off any gas leaks if shot from a distance. However, if the player shoots while standing in a gas leak, the explosion will occur just as with a "regular" firearm.