THe main problem isn't weight and velosity, its bullet constuction. The 300gr 375 has a SD of .305 for the nosler partition, the 300gr Hornady XTP has a SD of .232, so the 375 is likely to penetrate better. Add to that the fact that the 375 was designed for deep penetration in havey game at magnum velosities and the fact that the 300gr XTP was designed for pistol velosities, just like all other 429 cal bullets with the possible exception of the 265gr hornady designed for the 444. Even then the manufacturer doesn't recomend it for big bears, its just not designed to penetrat that heavy of game. The average use of the 444 os deer/blackbear and unfortunately this isn't a situation of one size fits all.
