I had to enlarge the square hole on my conversion cause the nut wasn't fitting flush with the receiver and the pistol grip wouldn't clamp all the way down.
So I just used a small diamond file and filed the front and back part of the opening until the nut fit flush.
This may be what is happening to yours.
I just found my Saiga 12 at the gunshow in Spokane, WA
Paid $400 + tax for it. There was only 1 there, and I have been looking for months.
This was the first week in Nov.
So there are a few still out there at a good price if you look around.
5/8 X 24 is what I am going to thread mine for.
It's the standard AR10 barrel thread so there are lots of different muzzle devices available
And I already own the die.
check it out
http://161.58.206.244/store/merchant.mv?Sc...ry_Code=akscope
http://www.surplusrifle.com/reviews2005/ak...pemnt/index.asp
I gotta a Burl style mount on my Saiga 308.
Works great.