The 270-grain GDFP should be an excellent choice for black bear in the the Deerfield carbine, as are the 250-grain Nosler Partition and Hornady 265-grain bullets; the only caveat is feeding. All three bullets perform very well in their velocitiy windows. Those who have not shot bear seem to think that they are almost bulletproof - that is not the case. Experienced bear hunters know that penetration is necessary, but so is expansion. An excellent example is the .35 Remington, which has for many decades performed very well on black bear with its rather soft 200-grain factory bullets.
Ruger warns not to use non-jacketed bullets in the Deerfield; I realize that many shooters do use cast bullets in this rifle, but they do so at the risk of functional problems in the future. Too, loads with an overall length over 1.61" may not function in the rather short magazine. Some have reported miss-feeds with ammo longer than 1.55". One of the problems with many good cast bullets is their excessive overall loaded length.
Perhaps a good compromise is the Sierra 250-grain FPJ bullet. It has a flat point for quick energy transfer, won't foul the carbine's gas system, and will penetrate deeply. And no expansion so it would keep the cast bullet boys happy too. :wink:
