69 grain TMK vs 77 grain TMK for defense use from a SBR

[brycewise]

I am wondering if 69 grain TMK would have better terminal ballistics in barrels under 10 inches over the 77 grain TMK because of the higher velocity?

My thinking is that if the 69 and 77 grain TMK's have the same construction and are both comparably on the "heavy" side... a similar impact velocity with the 69 grain and 77 grain would yield similar fragmentation and penetration results