I think you should invest into a Scourge Box, as it comes with a Splinter Cannon, and two other weapons that could easily be converted into one: the Haywire Blaster and the Heat Lance. Just cut off the weapon and glue on the Splinter Cannon of the Razorwing. This leaves you with three SC. As for the fourth... Hmm, how about glueing four Splinter rifles together? Like a Splinter Minigun?
Visit my project log [last update: February 10th]:The Ebon Fire