I've never had to hand cycle any weapon, ar systems included to get them to properly feed, or to break them in. The only one I ever had to do anything different with was my DPMS 308. It was failing to close on some ammo in the first few mags. My ex-wife sent me some Disotech XFR lubricant from Afghanistan. I cleaned it again and lubed it with the XFR and I've never had any issues since. This is the slickest stuff I've ever seen, and I refuse to use anything else now. It will stay on the bolt carrier and other parts for literally hundreds of rounds. I cleaned and lubed it last week and I haven't fired it, but it's still wet. It's kind of thick as well. A friend of mine that lives across the street has a kid that bought a Bushy M4 type and he lubed with clp and came over to shoot it. He had a couple of failure to feeds in the first mag. I brought it inside and let him lube it with the XFR, and it hasn't jammed since. He fired well over a half case one afternoon, which was the second time with it, no failures of any kind, and the weapon was still well lubed. My ex-wife tried a lot of other lubes, pro m7, CLP etc., and Brownell's sent her company some free militech, which was good, but the Disotech worked better for her in the extreme changing environments of Afghanistan. She never had any issues with her M4 with it. She had it jam on her twice, non mag related in the winter up in the mountain regions near Kabul in one firefight., She said she cleared the jam, fired a couple of rounds, and it jammed again, so she switched mags, and it did the same thing. That's why she went on a search for a better lube. Never had another problem with the XFR, or some of the others, but with the XFR the weapon seems to be way smoother. Just my .02.
On a second note, I don't think double feeding is a lube problem, but rather an extractor issue. Where are the cases going when it does extract? How far do they eject?