Mostly the cool factor, totally impractical.The thing is with the saiga receiver your a little closer to a rpk receiver and I can't help but think that the cartridge would bring some of the tack driverness with it.The thing that got me thinking about it was the thread comparing it to the new assault rifle rounds like the 6.5 grendel,6.8spc,7x46.We should have picked this thing up in the 50's.Especially if you look at it as the natural procession from the 8mm kurz or the 280 British.
Then with the saiga you have an inexpensive donor with the right size bolt face, rpk-ish receiver.I'd like to see some one go beyond the DIY and get artistic and creative.Kinda like some guys do with knives.
You certainly would run into trouble doing it in an ar(bolt).A saiga 308 bolt could certainly handle 55,000 psi.If it could cut a 2" group at 100yds I would be able to find satisfaction.Whats the real world accuracy with a saiga 308 anyway?3-4 moa?