can't see pic, aol asks for login. So your saying your rfb work before?

Any chance that there's some sort of small debris clogging the gas tap port in the barrel?

I would guess that when you tuned it in initially, if you did not do it with ONLY ONE round in the magazine, t-h-a-t would be the problem O-R maybe you duracoated something you should not have. I duracoated mine and am not having any issues several hundred rounds into it. Send her in if you can not find anything; They have very good customer service!

Quote from libra8 on 07/05/10 at 15:22:52:

 
I use synthetic oils, but I shoot a lot at a time, so the rifle tends to dry out. I'll generally just close the gas port a little more and it'll keep cycling fine. I do have one magazine that the RFB doesn't like, due to the feed lips.
 
Does the duracoat increase friction between moving parts? Maybe some got on a friction point like judcargile suggested?

Quote from imyomama on 07/21/10 at 13:12:33:

 
Calm down. I get sub-moa groups at 100yds with reloads. He's having cycling issues, and was probably working on figuring those out. It's hard to shoot tight groups when your semi-auto won't cycle, you throw off your natural point of aim every time you tinker with the thing. Additionally, not everyone shoots tiny little groups every time they go to the range. I shoot off-hand more than I do off a bench anymore, and my groups reflect this (although they are getting better).

How many folks are getting their RFB's duracoated?  That sounds like a real option, especially if the new coating isn't causing function problems.

I ran a test on mine to see how many rounds it would take to foul up enough to start affecting reliability. I was firing British Aerospace 7.62 Nato 150 Grain surplus ammo, and started with a cleaned and lubed rifle.
 
After 18 full magazines or ~360 rounds I had my first FTF, just didn't quite close the chamber. I racked it in, fired, and another FTF. Racked that one in, turned the gas knob up one click and fired the rest of the 500 rounds I was willing to spend on this test without a hiccup.
 
The adjustable gas system on this rifle is a valuable tool.