RE: Is .308 enough gun
The biggest rifle in the world won't stop a grizzly charge in colse quarters unless you hit the spine or brain. If you can hit that spot then any good sturdy bullet will do the job. Its been done many times with the 30-06. Before the 338 and 300 Mags ever came out, hunters took the big bears every season with the 30-40 krag, 30-30, 270, 30-06 and many with the 303 and 7x57 mauser. My grandpa killed several with his 44-40. Many more were killed with the 45-70 and many other black powder cartridges. The 308 with 180-190 grain bullets stack up pretty well against many of the old proven calibers. The fact that his rifle is a semi auto would concern me more than the caliber. Most grizzly country is not auto rifle friendly. Besides many hunters hunt dangerous game because its dangerous. If you do some checking around you will find that Grizzly and polar bears have been killed with rifles much smaller than the 308. Like the 22 Hornet and 218 Bee. I wouldn't try it but its been done. I have used the 30-6 and didn't feel undergunned at all. You got to hit them right. Thats far more important than the gun you use. Bears have eaten magnum totters too. Bears are not impressed by ballistics, only by good shot placement. If I go again it will be with the 45-70.