I just got my Norinco M1A tonight, and discovered taht the mag catch won't quite engage (tried on a USGI mag, the only one I have right now).  I broke it down into the trigger group, receiver group, and stock and slipped to gether the trigger group and receiver group and it will lock in OK if that means anything....

The mag is in firm enough that it won't pop out, but I don't have to use the mag catch to remove them either.

My guess is I either need to take a hair off the top of the mag catch or try another stock?  Any help would be appreciated.

Wood or Fiberglass stock?

Wood.  Actually it looks like the wood may have slightly compressed at the trigger pack, and the marks on the mag look like it is less than 1/32" form engaging.  I bet If I shim it so the trigger pack sits just a tad lower it will work fine, at least until I can get a synthetic stock....

Sounds about right, I always keep the trigger group out of the rifle when it sits in my safe

Definitely was the stock being compressed a bit at the trigger group- when reassembling after cleaning I wedged two layers of an old business card between the trigger group and the stock, and the magazine will engage now.  The wood is pretty soft and appears to have compressed a bit over time.

The business card trick will work for now, and I have a Fred's synthetic and Excellent grade birch on the way as a more permanent solution.