I dunno where this goes, maybe it's even just begging for a lock, but here goes...
Before you suggest something radically different regarding weapons handling, please think about whether or not you can do it in real life with a real firearm.
No, paintball guns, airsoft guns, etc. do not count. The fact that in airsoft wars a full-auto G3 mockup is used as a machine gun should be enough to trip red flags in your logic centers (they're supposed to be in your frontal lobes, please see a neurologist if you can't find them).
Try sprinting and cycling the bolt on a full-length military style bolt-action rifle at the same. If you drop it, I'll cry, because old milsurp rifles don't deserve that kind of abuse after serving their time.
Don't make me cry by trying it, because you probably will. Unless you have the bayonet on, in which case I will cackle wildly as you stab yourself through the <appendage>.
On automatic weapons: try renting one at a range (in the US, look for Class III ranges, they'll often have SMGs you can rent) and firing it from the shoulder, using the sights. See what your patterns look like. Yes, patterns, because unless you are damn good, you're not going to get a "group" firing in bursts longer than a few rounds. Now try firing it from the hip, "walking" impacts into the target by watching the dust kicked up from impacts