Since many Grizzley have been taken with the 30-06( including mine), the 300 Win Mag should do the job just as well. The old 30-40 Krag worked well for my Granddad and uncles before me. Use the 200 Grain Partition or the 200 Grain Barnes X bullet. The 308, 30-06 or the 300 Mags will do the same job out to 200 yards. The Magnums add another 100 to the range. I have used the 300 Win mag and 300 Weatherby Mag both. Have not tried the 300 WSM but its has close to the same numbers so It would be a good choice too.