First off, thanks everyone for all the great info on this site!
I finally got to a range where I could really let the Saiga 12 go (my local one doesn't allow shotguns).
It was a load of fun, it appeared to cycle bird shot 100% on the low brass setting, but when on the high brass, I did have some problems
my saiga doesn't seem to like Remington slugger rounds (they sometimes won't eject fully), which I think is the round's fault, the recoil felt about half of 00 12 pellet buckshot I had staggered with it in the mag.
the only other problem I faced was when I tried to load a round