You can kinda see the rib in the back,, they lock in just fine, I'll post a range report when I get a chance to shoot them.
Edit- they have no stamps or any markings that would suggest their origin.
Sgt. of Marines, 5th Award Expert Rifle, 237/250
1st Award Expert Pistol, 382/400
D Co, 4th CEB, Engineers UP!! OEF 21JUN-20SEP2011