[Drakker]

I ordered from Airsoft Pro three times so far, if I remember well it took roughly 2 weeks every time.

I don't know anything about PPS barrels either, so I can't comment. But the thing with 6.01 barrels preventing BBs from getting spin is bull. The BB gains its spin from the hop-up rubber. It might or might not get extra spin as it rides on the ceiling of the barrel, no one knows for sure yet. Even a 6.00 barrel will not reduce the BB spin significantly.

In an inner barrel, the tightness of the bore determines how much extra power the BB gets. The smaller the bore, the less air escapes on the side of the BB and the more power it can get. On the other hand, in larger bores, there is a lot of air escaping around the BBs forming a kind of air cushion, which prevents it from hitting the barrel too often and getting side spin, thus giving it a straighter trajectory. Airsofters now generally agree that larger bores barrels are more precise. The reason why people think that tight bore barrels increase accuracy is because they used to compare crappy stock barrels in the days with high-end consistent bore barrels. Tightness didn't make them more accurate, it was the quality of the bore that did.