cbr-
My S-12 was made in 2009. It has 3 gas ports and will cycle 1 oz loads with no problem on setting "2". That said, before about 200 rnds of break-in it wouldn't fully cycle anything, including buckshot. I would suggest you buy at least 200 of the cheapest 1 1/8 oz loads you can find, and shoot em all. There's no excuse for not shooting the he** out of that gun. Just loading up a couple mags & blazing with it is fun enough; once they're broken in they cycle like lightening.
Remember that it is the weight of the payload (and the powder charge), not the size of the shot that determines recoil & gun function. Remington "gun club" with #9 shot will cycle your Saiga just as well as with #7 1/2 shot, or even #4 if they made them with that size.
Last I checked, Dick's (yes, I know they suck) had "gun club" shells on sale $5.98 a flat (10 boxes of 25), with an additional $10 mail in rebate. You won't find factory ammo any cheaper than that. Save the hulls (at least the ones the Saiga doesn't munch) and send 'em to me.
Have fun, but don't expect too much out of the Saiga. I've shot skeet with mine several times, but it's hard with a gun so light & short. It will also be lousy for trap with the non-existent choke. You'll still have fun though, my Saiga always makes me grin.