You are correct.
M855 varies wildly in weight and penetrator placement.
Cross-sections show significant gaps in the nose, off-center placement, etc.
Personally, a good 55gr round just about does it for sub-300m engagements. Even better is the 52gr tactical loads that use the V-Max varmint bullet.
Thanks, I didn’t know that someone did cross section analysis. Do you have a link? I’d like to see it.