The Saiga does not have a standard handguard retainer. So to use most of the handguards, you have to add the retainer.
I ended up ordering the $80 retainer from Dinzag.
http://www.cheaperthandirt.com/49797-64126-1872.html This is the only handguard I've seen that doesn't require a separate retainer. And it works with the stock gas tube.
It looks something like this when installed.
http://mywebsite.register.com/db4/00329/el...nderfolder1.JPG