SR4 Firearm Design Rules, Or custom creation rules of any sort Options

[Balfuset]

I've recently been getting a few fan-made supplements for the older Shadowrun editions, as while I majority play/run 4th edition I like to make use of fluff and other things from the earlier editions. In the course of this I found a few custom-designed guns for 3rd edition which lead me to the firearm design rules in Cannon Companion.

I was wondering if there were an updated set of rules (either fan-made or official) for designing and pricing custom firearms for fourth edition. I could try and convert the rules from CC, but I'm not generally that good at such things and there are sufficient changes in general statlines, let alone rules, that make it quite a job that I'd rather not do if there's already a resource out there for me to make use of.

Granted, 4th edition has practically every kind of gun you'd ever need, but I'm currently running a high-level corporate game, where my team are essentially playing the special ops of company men, and I think it'd be nice to be able to throw some experimental SOTAtech at them once in a while, be it armour, weapons, vehicles or drones, or anything in between.

So if there are potential rules for custom design of equipment (pre-modification as presented in Arsenal) I'd be really appreciative if people could point me in the right direction! ^^