I was just looking again at my French guns. Maybe having a thumb notch is mandatory for old military rifles, but it sure seems to me both the MAS 36 and the MAS 49 types would have been much stronger and more rigid without it. Also there are deep and not particularly necessary grooves running vertically inside the magazine well that just about cut the receiver wall thickness in half. It's bad enough to have the deep thumb cut on Mausers, but at least they're front locking.
Also, the 49/56 locks by tipping the rear of the bolt down, and it's held down by the bolt carrier. But there really isn't all that much holding the carrier down. There's a rail on the left side engaging the receiver at the front of the carrier, and the receiver top cover over-laps it at the rear by about 3 hairs worth.
I suppose those darn French gun designers must have known what they were doing, but I suspect they got some kind of thrill out of this dare devil engineering.
Pogo, I'm glad to hear somebody else had slamfires. The first day I got mine I was checking it out with live ammo (in my usual careless fashion) and shot a hole in the kitchen floor and blew out the basement window.
So much for Mr. Gun Expert.