User blog comment:Dragonzzilla/Mass Effect 3 Weapon Modifications/@comment-1388547-20120410224225

Javelin/SMG is probably a good combination, since you have something to shoot with at all ranges. Obtaining the Javelin may be the problem here... As for how to mod your weapons, that's entirely a matter of playing style. My personal preference is to have one primary weapon (shotgun for Vanguards, which are my favorite class, sniper rifle for your Infiltrator) that I equip with mods that make it better at what it already does well, and a lightweight secondary weapon (heavy pistol for Vanguard, probably SMG for Infiltrator) that's designed to fill in for the weaknesses of the primary. For my Vanguards, I take a barrel extension and shredder mod on the shotgun, and a barrel extension and scope on the pistol. For the SMG, the ultralight materials mod may be a very good choice too.