Due to the high S.D. of the 160 gr bullets,I would not hesitate to use the 6.5x55 on grizzly. Especially if you know the gun and are very familiar with it. It would (with 160's)be a better choice than 270,280,308 etc. shooting bullets with a S.D. a lot lower, and many grizzly's are shot with those rounds each year. 30/06 shooting 200's and 220's would,to me anyways,be the next stop along the cartridge line up that would do as good or better than the 6.5 x 55 and of course after that the big magnum 338 and 375.
I would think the 6.5/160gr combo would work better than a 300 shooting 165/180 gr. I believe in a bullets S.D. and think it is an important ingredient in a cartridges make up.
Know your gun and its limit and shoot within it and you will be fine.If you feel you need more gun go to a 30/06 with 200gr+ bullets or to a 338Win mag/250gr.
