Just hit Megaton, trying to get good karma only, so can't steal from Armory. All I've got so far is 10mm pistol and Assault Rifle (with like 12 ammo only). Can you go certain places to get better weapons (without having to buy them since i have like 100 caps) or is finding weapons completely random?
SpringVale School will have quite a few, it's relatively close to Vault 101. Try Super Duper Mart for others, as quite a few also. xD Rivet City will be revealed to you shortly, along the route to their, set a marker from the front of megatron and follow. Big Guns-Energy Guns-Melee Weapons and Small guns will be encountered nonstop on the way.