Yes it was originally designed to use the .276 Pedersen with a 10 round clip. Then it was re-designed to use .30 M1 ammo with its 174.5 grain BT bullet at 2640 fps after MacArthur said use the W.W. I ammo. All developement was done with this ammo. Said ammo(actually developed for MG's) eventually proved to have too much range for National Guard ranges of the time. .30 M2 ammo was developed(approved and adopted in 1940) with a 152 grain FB bullet at 2700 fps, subsequently upped to 2800 FPS to match the ballistics of the .30 AP's 168 grain bullet.
King Obama refused to allow the Korean rifles back into the U.S. They were never coming this way. South Korea wants U.S. currency, not Canadian.