Somehow i got into making myself a little subfaction, already got a combat armor, handgun and hopefully transport.
But I've been trying to create a new assault rifle by first creating a copy of the infiltrator from The Pitt. It works fine except the firing rate is absolutely hyper, i could count about five times a minigun's speed. I set its firing rate to 6.0000 in the editor, yet no matter what I change it to it always reverts to some sorta 'KAMEHAMEHA BULLETHOSE'.

This is getting annoying, any ideas?

Not sure what changes you made to the stock infiltrator, but that definately doesn't sound right. I went in just now and created a custom copy of that gun no problem, so possibly your custom form got screwed up somehow. Maybe try remaking it starting with a fresh copy of the stock gun. The only things I changed on the custom gun was the weight, health, damage, min & max spread (0 to 0.1), and min & max semi-auto fire delay (0 to 0.2). Just for kicks I gave it a custom 556 projectile set to explode on impact, and then gave that projectile a custom explosion made from a copy of the pulse explosion with its settings scaled down to about 1/6 of what they were. No problems with it at all.. in fact, it's a rather fun and addictive weapon that mows things down rather nicely. I will, however, be removing the scope on it because the zoomed crosshair wander annoys me and is much less effective when using zoom as binoculars.