I have a 20ga Saiga...with an Alliance Armament 23rd drum...I've also got metal 10 rd mags for it too.
Also... there are several other 10rd-13rd mags out there on the market for the 20ga Saiga's now......and 410's just don't do it for me.....so don't let the naysayer's discourage you if you're really wanting a 20ga !
It's true that there isn't a "Cheapy" type drum available for the 20ga right now...the alliance armament drums can run over $300 (cheaper used tho)...but they are very high quality (billet aluminum) and you don't have to worry about them cracking or breaking as much as you