Though I would love to shoot two rounds of Trap without having to reload, the largest magazine available (at least that doesn't cost almost as much as buying another shotgun) holds 20. Wraithmakers hold up to 30, but they're almost 400 dollars. Anyway.........
Shruggerxd sort of explained it. In order for the Saiga shotgun to be imported, Izhmash had to make it into a "sporting" gun that didn't have a pistol grip. So they added a linkage to the trigger mechanism, moved the trigger group to the rear of the receiver (like a backwards bullpup,) and slapped on a Monte Carlo stock. Now, if you want a pistol grip for your Saiga, you can do two things. The first is to get an external receiver block that attaches the pistol grip to the rear of the gun without moving the trigger group forward. This is what a Saiga Shotgun looks like with a pistol grip, but without the trigger group moved forward:
The other option is to do a pistol grip conversion, where you drill out two pins, grind off three rivets, remove the stock trigger guard, throw out the trigger and most of the internals, and install a new trigger guard and trigger. This moves the trigger group forward, and allows a pistol grip to be attached beneath the receiver instead of behind it. This is what a Saiga shotgun looks like after a pistol grip conversion:
Converted Saigas have much better triggers, the whole package is more compact, and is a lot better balanced.
Do yourself a favor. If you want a pistol grip, do the conversion. You will ultimately save a lot of money on furniture for an unconverted Saiga, because you will ultimately decide to convert it anyway.