I'm sitting here thumbing through a ak47 magazine that was put out by guns&ammo called AK47, there's an article in it titled Russia's greatest round. (page 62) on page 69 it has a energy/ trajectory comparison between the 7.62x9, .223/5.56  and .308. I'm not interested in the comparison but the trajectory chart got me to thinking that almost every time i look at a ballistics/trajectory chart for the 7.62x39 i see differences between them.

I realize that depending on powder/bullet loads there will be differences in what the charts look like. Is there anything close to being a standard for the 7.2x39 ?