So mine came in last night, what a cool little gun.
The gun is not your typical pump action like a Remington 870... for starters, there is no mechanism to lock the bolt closed until you pull the trigger or push the bolt release. The spring keeps forward tension on the pump, so it stays in battery without assistance, but can be rapidly pumped at any time without actuating the trigger or a separate button. The feeling definitely takes a few minutes to get used to, but it is a very neat feature.
Mags are reasonably close to the size of a standard 30 round AR mag, but thicker. A standard double AR mag pouch will likely hold one of these mags. Mag changes are quite smooth, I like the straight insertion, and the release lever is nice and large, but not in the way.
I will likely try to modify some kind of hand stop onto the pump of the gun as others have mentioned, to keep myself from doing something dumb.
The stock is only OK... it works, but it could use some refinement on the buttons for the adjustments, some features seem poorly thought out and rushed compared to the rest of the gun.
Safety is incredibly stiff on mine, not sure if that is a common issue or not. I'll see if it will work in, if not, I will do some fine tuning on it to get it moving smoother.
All in all, the SAP6 is an awesome little gun for a good price. There are a few small details that can be improved, but I am happy so far. Can't wait to get it out to the range!