From what i understand the claymore as we know it didnt originate untill the vietnam ambush, and primarily used either in two roles
It was an ambush initiator, due to the fact it could be quickt placed and the large frag radius made it perfect in a jungle where most explosive charges would have been usless. And it was used to secure perimeters, placed roughly 50m forward of the line.
Im sure i will be corrected on this, but figured id give my two cents since ive actually been able to use them. Hell of a bang for sure. And certainly not what you get inthe movies