As far as "Full-Auto"? Changing gas system parts is unlikely to to have any effect on this. Mine cycles FAST! I can put 10 rounds on target in 1.8 seconds. With 9 pellets/shot (OO buck) that equates to a cyclic rate of 2700 Rds/min. Minigun rate. Faster than the AA-12. WHo needs full auto?
There are two different saiga 12s. The unconverted ones had a bad 2 port gas plug system, mine was this version. But, I put a autotac plug, corrected the gas ports, runs like a champ. The newer saiga has that krink style gas block.