If you are playing the original Fallout 2, I'd stear clear away from all types of laser weapons, especially the Gatling laser.
The reason is that of all the damage types, Laser is resisted the most across a large amount of armor, especially Power armor and all its variants, meaing at at the end game, unless you are capable of scoring constant armor-ignoring crits (via the Slayer perk), Laser will do very little damage compared to the ammo it consumes. In fact, under most circumstances:
1. Burst weapons will have most of its shots miss their intended target unless the critter you are shooting at is literally at the next hex. This could be compensated by higher skill levels, but at least around 100%'s, that is true from my experience
2. The fact you need slayer perk for this weapon to work speaks for itself. Slayer makes nearly all ranged weapons brutal to use against even PA foes, but Gatling laser is only useful with it. Even then, you could probably achieve the same result using single shots like Pulse Rifle to similar effect at much lower ammo costs.
That said, if you want a way to replenish your Microfusion cell supply, here is what you can do (this is assuming you progressed to the point where you have access to San Francisco)
1. 'Farm' Hubologists outside of SF, the encounters will always yield 2 Hubologists that wield H&K G11E. Killing them will yield large ammounts of Caseless ammo (which is deemed rare if you dont farm it), and the G11E's sell for $8000 each. Killing Hubologists have no impact in the game whatsoever. It will not affect your Karma, will not affect your relations with Hubologists in SF or NCR in any way, and other Hubologist NPCs in random encounters will be completely oblivious.
2. The best places to turn in your guns for Micro Fusion cells are the 2 merchants in SF (888 and Flying Dragon), and the 2 merchants in NCR (one by the entrance of NCR, and the Stockman's shop in the NCR Bazaar). They all have a good chance of stocking large amounts of MFC. With all of these merchants, make sure you search all of their tables/bookcases and look at their barter screen to check if MFC have stocked with them.