Not saying the old 'standard' Brenneke's won't kill bears - they can- but even they aren't magic where penetration is needed.
This one was plucked from the offside shoulder of a small bear take 5 years ago in a DLP incident. No bones other than ribs were broken and shoulder/chest tissues alone were involved.
My then-9-year-old with the eager victim's salvaged parts.
Projectiles matter; buckshot barely qualifies in my opinion. (Give me some rubber buckshot if I'm going to be shooting buckshot at bears; avoid the DLP stuff at all if possible. )
Sometimes, the air you 'let in'matters less than the air you 'let out'.