There was an earlier thread about this- does anyone have the link? I did a search but couldnt find it. My problem:
I am doing an AMD-65 build with an OOW reciever and it looks like rails that should slide into the rear trunion are too low, causing the receiver to bulge out, and in turn not alowing the top cover to snap into place. The front lines up graet with the front trunion, but the rear has issues. Has anyone else had this problem.
Thanks,
Dean

I'm doing the same build.  I filed the rear edges down so that the width of the receiver with the trunnion installed would be the same as a Norinco I have.  I also fitted it so that the sides would lie flat along side of the trunnion. My top cover also spreads out when I try to put it on. I don't know if the trunnion is too low, or if the cover has been collapsed slightly and needs to be spread out.

I have the same problem, I think their jig or whatever is off a tiny bit.  Next build I will go and get another blank from Robert Ibe at Bentmetal. His measurements have always been dead on and things fit.

The bends in the OOW receivers are not as sharp as European spec receivers.  The more rounded bends in the OOW cause the sides of the receiver to bow out, as the grooves in the trunnion and stock tang have a sharp corner.

The easiest fix is to file the bottom edge of the grooves in the trunnion and stock tang.  A 45 degree bevel filed on the bottom edge of the groove will allow the receiver to fit properly.

Trimming the receiver rail off will work, but is not the best idea.  The narrow portions of rail at the trunnion and stock tang are there to stiffen the sides and prevent snagging.  If the sides are just flat against the trunnion or stock tang, the metal can snag something that is rubbed across it.  That narrow section of rail that bends into the groove removes the possiblility of snagging and stiffens the sides.  0.040" steel is pretty stiff stuff, so bending a corner out from the receiver should never be a problem.  The grooves just capture the sharp corner of the narrowed rail.

While trimming the narrow portion of rail off will not cause functionality problems, the receiver is intended to fit into the grooves in the trunnion and stock tang.

I only have 2 complaints about the OOW;  The lowered safety selector hole (7.62 receiver only), and the more rounded bends.  They make a nice rifle and the other specs are dead on.  I also like the fact that the trunnion and stock tang holes aren't predrilled.  You can get a perfect fit for your parts without having to weld up or elongate existing holes.

Yup, a AK build is all about having the right files and hammers on hand... nothing is perfect, and it all needs fitted. No biggie, just take your time...