Different countries have different variations of the SS109. The UK runs a thicker jacket than the US so that their rounds don't fragment in flesh (their lawyer's version of Hague convention compliance). In the end, they all work, with the nod going to the Israeli's for consistency based on some sampling I've seen that lack an air gap between the steel penetrator and jacket at the nose.
Odds are if you bought it in the US and it has a green tip it is Lake City pulled bullets. Nothing wrong with them.
Machine guns are awesome until you have to carry one.