I bought a Romanian underfolder kit and a OOW receiver, when I go to put the rear trunion into the receiver it  doesnt fit and just goes in like a wedge pushing the sides of the receiver out at the top and pushing in on the bottom. I guess I will have to mill the trunion down to get it to fit. Also I have a really nice 2mm gap at the bottom of my forearm and receiver and completly flush at the top.  I didnt have near this problem with OOW receivers before on my other 2 builds.  Has anyone else ran into this on their recent stuff?

Are the rails on the top of the receiver fitting into the grooves on the trunion?  If not, you might want to take a triangular file and widen the grooves a bit.

As long as the receiver is still the standard stamped .04" thickness you can use this method below.
I had a similiar problem with an rpk trunion I used for a build.
If,....Like I said the thickness/gauge of the metal is .04".
Fine sand the top rails smooth where the trunin fits, use a small Thin flat head screw driver on the inside of the grooves in the trunion. With some light tension pry back and forth very carefully opening the area where the top rails slide in.
You can use a medium to heavy grit sand paper (folded in half) to smooth out the openings of the trunion. Keep testing to fit.
And it should slide on with very little problem.
You can also file (lightly) the insides of the receiver rails where the trunion fits.
Just becarefull while prying, not to break the tabs of the trunion itself.  And remember don't take off too much. This could effect the overall inside dimensions of the receiver and cause the charging handle to stick when fastened.
Hope this helps,
-Shadow-              

on the OOW's (aren't they 1.2mm?) I have built I have found it necessary to widen the groove where the receiver's lip goes into the rear trunion. (aren't all comblock receivers 1.0mm) It's as simple as running a dremel's cut off tool thru the gap to widen it. The same issue is present on the front trunion in a lot of cases.

Quoted: on the OOW's (aren't they 1.2mm?) I have built I have found it necessary to widen the groove where the receiver's lip goes into the rear trunion. (aren't all comblock receivers 1.0mm) It's as simple as running a dremel's cut off tool thru the gap to widen it. The same issue is present on the front trunion in a lot of cases.

+1....  This is what I had to do with my AMD-65 build on an OOW receiver...

Quoted: I have been told before that building a good AK is all about having the right files and sandpaper.

And a dremmel with lots of cutters, wheels, and attachments for it!