Strange problem with Marui BB retention.
 

So I've upgraded my hop up rubber (basically new), have my hop up set close-ish to max, and made sure the inner barrel and hop up wasn't sloshed with silicon oil. The problem is, the first BB of every mag rolls out of the barrel when once I rack the slide. Its just the first BB, as all the others fire off fine. If I stop firing mid-mag, and point my gun down and shake no BBs fall out. I think I've followed all the proper protocols for this problem, but it doesn't seem to work.

My question is...

Has anybody else experienced this before? Are there any other things that I should try that I haven't already?

Innards:

- Tanio Koba Twist Barrel
- Firefly hop up
- KM High Flow valve (mag)

I noticed my Airsoft Surgeon Nozzle is sticking a bit to the inner barrel as I rack the slide. Does this have anything to do with the problem? How do I fix the stickiness?