Sounds like you might have caught the bug.
You might be right about that. Just what I needed.
Seriously though, thanks for the input,
RM. I appreciate all of the expertise you guys have been so willing to share. Just the detail I got by filling out the surveys makes me feel like half an expert now.
Today the fourth magazine catch turned up, along with some ammo belts and a sling that looks like it's never been installed. The new mag catch is tombstone shaped, so there's a nice 3-1 match. I didn't see anything in the reference material about the shape of the magazine catch changing between generations, so I'm guessing it's not a critical difference anyway, but having 3 and one makes them line up nicely.
I also turned up some 30-round Zytel magazines, also from Cobray, to go with the aftermarket stocks. Now it's a complete package except for one missing original magazine.
The Zytel magazines that were still in their wrappers each came with two of these little round knobs. Anyone know what they are?