Technically, clean it once you start seeing reliability or accuracy degrade, however good lubrication is FAR more important than a clean weapon.
Google Pat Rogers and the Filthy 14.
He put something like 25,000+ rounds of 5.56 through a BCM AR on an intensive shooting schedule (1300 rounds every few days) with just lubrication(SLIP2000) and preventative maintainence on wear parts(extractors, springs, etc) before it started to have seriously have malfunctions. He cleaned it and ran it past 35,000 rounds before retiring it.
We ran 20,000 rounds+ of .22lr through a Marlin 981T over the course of like 2 years in s**tty conditions on the farm, just hosed it down with WD-40 or oil once in awhile, and it was good to go. Accuracy went to s**t by the end but it never choked on standard bulk pack ammo. Same with the 10/22, we probably put 8k-10k through that sum##### before tearing it apart. We wore out 2 butler creek banana mags before we cleaned it and the gun still ran fine with good mags. My Beretta Xtrema2's run like f**kin sewing machines and i dont remember the last time we cleaned them. Maybe twice since we bought them 4 years ago. Good lubrication is the key for any moving machinery.
So unless your shooting bulk corrosive goodness, i would just lube the hell out of your guns and shoot them. I think we all know what happens with corrosive ammo and moisture, but its not as serious as everyone makes it out to be. On the farm I give my 858 a quick once over every few days if im shooting alot and its just fine. These are supposed to be military rifles, not benchrest queens.
As long as you dont put them away dirty and oiled to all hell for months at a time, i think you'll be fine.
