In time? I thought this was a hypothetical predator vs. earth military discussion. *Re-reads*
I was thinking you strap a (very expensive and somehow shock-resistant

) camera to the gun, plug it in to the iPhone or whatever processing power the marines have on them, and the computer compares the actual image to the expected image (based on previous footage), searching for that specific blurry effect. Then it draws (either on a screen on the gun, or better yet on a Halo-marine-style helmet HUD) an orange silhouette where it thinks there's a cloaked predator. Yes, I'll bet we can do that if not right now, at least in a few years.
Machine guns are either bolted down or on some kind of bipod. Infantry fire assault rifles in very short bursts.