Background
The Burning Wheel system grew out of a homebrew of Shadowrun 1e, switching to a fixed TN in the process (this was before SR4 went fixed TN). It is "grittier" than Shadowrun in that the characters have abilities closer to human norm, it isn't as over the top. It also has things like Circles and other ways of resolving conflict that are very useful for a Shadowrun type game, as well as its "use a Skill to advance it" system. I've actually tried importing Circles and Resources into SR4, with mixed results.
What I've Built So Far
Now I'm coming at it from the other direction. A huge barrier to this though is that the combat systems in BW are NOT made for modern warfare and the combat sub-systems in Burning Empires isn't really built for the personal level of action of Shadowrun (because BE isn't built to be a game focused on individuals like most RPGs are). So I went back to the drawing board and blew up Fight! and Range & Cover to create a combat sub-system from scratch that mixes guns and knives in modern combat scenarios typical to what you'd see in Shadowrun games.
I call it Streetfight!, and I've done some initial work with actual play. It's gone very well, it gives a tactical firmness to combat that is missing even from Shadowrun while allowing a hand scribbled map and not requiring you to break out the tape measure to play.
Where You Come In
I'm looking for people, preferably at the start with some exposure to Burning Wheel play, to further refine this. It isn't a full 6th World implementation yet, I haven't laid out the Lifepaths or how to add metahumans. I also don't have the decker/hacking rules ready for people to test. The decker/hacking is coming soon though because the live play of combat feels close enough that I can assume it as a solid base to tailor the decking/hacking to. One cornerstone I laid out at the beginning of this is being able to do that scene on the front of the SR 1e/2e core book! I'm confident I can do this now.
If you have questions shoot but I'll warn you I'm going to be a bit vague because I don't want to poison playtesting. If you have one or more other folks that together you can try this out please email me at send_junk_to_me_now@hotmail.com. I'll email you the 6 pages plus the scripting sheet.
QUOTE ( Overview Exert)
Martial conflict in Burning Wheel is designed for a pre-Industrial society. Streetfight! is a Rim sub-system intended to integrate hand-to-hand and small arms martial conflict in Industrial-to-near-future settings. It supersedes Fight! and many uses of Range & Cover (R&C). As a counterpoint to Fight! and R&C, Streetfight! has more emphasis on physical location and objectives while providing the traditional threat of imminent, chaotic death. It loosely correlates to what modern militaries term Close Quarters Battle/Combat.
On The Rough Streets
The overall combat area is sub-divided into smaller locations called Positions. You may associate objectives with Positions. These are a form of Intent. For example one or more PCs must reach a marked Position to retrieve a Gadget or Hostage and then escape by each reaching a Position at the exit door. The players may agree that if there are no able NPCs in or adjacent to the Position when they escape there is no subsequent chase. Not every Intent needs an objective on the map. "I'll execute every m*$&@#%*!king last one of ya!" is a perfectly valid Intent for Streetfight!. However most maps will identify at least one exit point that will signal the end of the Streetfight!.
On The Rough Streets
The overall combat area is sub-divided into smaller locations called Positions. You may associate objectives with Positions. These are a form of Intent. For example one or more PCs must reach a marked Position to retrieve a Gadget or Hostage and then escape by each reaching a Position at the exit door. The players may agree that if there are no able NPCs in or adjacent to the Position when they escape there is no subsequent chase. Not every Intent needs an objective on the map. "I'll execute every m*$&@#%*!king last one of ya!" is a perfectly valid Intent for Streetfight!. However most maps will identify at least one exit point that will signal the end of the Streetfight!.
What Is In It For You
If you appreciate how Burning Wheel fixes some deep seated problems with playing RPGs but still want to get your 6th World on, and are dismayed by the lack of modern combat support in Burning Wheel, here's your solution!

Thanks for your time reading this and I hope to hear from you soon.
.dwight