As a defensive load I assume you mean human or are we talking dangerous game.
Seems to me those Barnes bullets while some of the finest hunting bullets made, have possibly too much penetration and will probably result in a pass through 6.5 cal hole with possibly no expansion.
You may want just a conventional exposed lead tipped bullet which works for " thin skinned,non dangerous game" which homosapiens are known as.
A medium weight for caliber that moves fast will probably work.
I watched 100's and 100's of 55grain FMJ's sail through those thin skinned non dangerous game with only little holes depending on location....and not a real impressive result. Follow up shots were usually enough. I will say I have seen much larger more powerful rounds also fail with single shots.
Led us to believe nothing is a guarantee and that two legged game high on some sort of speed can take a few.
We just used a few shots to be sure and then a few more....
Your results may vary but I have given you eye witnessed results and possibly the other replies also have eye witness accounts.
Shot placement is critical but sometimes you only get snap shots as these rats ran about.
Yeah I bailed out of the Golden State 30 years ago