I have a Saiga 12. As was posted by others the adjustable gas ports are set so all but the light birdshot low brass loads work off of #1, flip it to #2 for thos light load shells, as the ports are opened more to allow gases to help recyle the action.
I am about to use my Saiga for my first Texas Hog Hunt this June. I use the factory 5 round mags, but have a couple of 10 rounders here at the house. No limit in Indiana for mag capacity when hunting anythiong other than waterfowl. I wonder what a game warden would say if he came across me with my Saiga after deer...with a 30 round drum on the shot gun !!!
Early on with this gun I had a few FTE's with light Federal loads...cured by checking to be sure I had fliped the plug to point 2 on the dial.
Here is my Saiga. One of the best $450 I have spent.
Tactical Saiga 2010.jpg