Magazine Pouch Question

[artu44]

Yes, Limey is 90% right, but I think the real reason for having added the snap on 1918 mounted belts is just to avoid separate lines of production for the mag pouch. They made zillion of them and to be forced to divide production in two woukd have slowed the chain. The pouch is assembled with a snug fit on the belt (you have to suffer a lot to pass the buckle) and cannot slip.
In the pic a Mills 1917 and a P.B. CO.1918