Will be fine for a sporting rifle. If headstamp is any date earlier than 1952, treat as corrosive primed. In addition to US milsurp, there is some Greek milsurp out there that is pretty good stuff.
M2 is not always AP, some is ball. If it has a black painted tip (as sold by the CMP) that IS armor piercing- steel cored bullet inside of jacket metal. Bear in mind that what it will penetrate is based on how far away it is, and no, doe not make tanks go up in flames- will tear the hell out of a truck.