For me, the issue with hitting that 8" target wouldn't be the ammo, it would be those AK sights (I'm just assuming that's what we're talking about here).
Anyway, what I would typically do here (regardless of what rifle) would be to put a large sheet of cardboard out at 150 yds, with two large circles drawn with a sharpie pen on it. Then fire both ammos, from a rest, at each circle. This will give you reliable, consistent groups, and quickly tell you where each round likes to go, while avoiding the time and frustration of wasting ammo just barely missing the steel gong, and trying to guess exactly where they're hitting.
5 rounds of each ammo, should quickly answer the question.