Well, in Fallout 1 the most powerful weapon was the Turbo Plasma Rifle, iirc. In Fallout 2 it was the Bozar, which took a Big Guns skill to use effectively.
IIRC, weapon base damage translated differently depending on the armor type. In particular, in Fallout 2, the advanced power armor had slightly lower damage resistance to normal damage than it did to plasma and electrical (the latter mattered for pulse rifle). On top of that, gauss ammo had a very high AC modifier (making critical hits easier), and also a high DR modifier (reducing effect of enemy armor). So it was much more efficient against e.g. Enclave soldiers in power suits than its base damage would suggest.
In practice, with a build that maximized small arms from the get go (which also made the early-to-mid game easy), and invested stat points into Perception for those crits, by the end of the game you would be killing Enclave patrolmen with one-shot eye criticals more often than not, making any extra damage kinda moot.
(As I recall, gauss vs pulse is a long standing holy war in Fallout 2 community.)
