I only own one big game rifle, a rem 660 in 308. Even with its short barrel(18" or so) I have taken two of my elk @200yds+. It is aextremely accurateround, and since you are not comfortable shooting over 300yds, would be enough for any big game specie in North America. Personally, I would opt for a larger Mag for brown bear and maybe Yukon moose, but 308's have taken plenty of thoe in the past.m As a veteran, i have a close relationship with the 308(7.62 NATO), and know that even in a rifle such as mine, it isplentyenough for most everything. It is all a matter of bullet selection and proper shot placement on the larger game. Personnaly, I shoot 165gr Swift Scirrocos, out of the box my first year, and handloads this last year. Out of the box first year I took my first cow elk @ 200-225yds running, and hit vitals with 2 of 3 shots. Good enough for me. One round shatered a rib, went through a lung, through rib on other side and then shatered the forearm. She only made it about 100 yds downhill and was done. Three days later I took my first doe @ 15 yds and she only went 30 yds and was done. Great blood trails with all. I have had great results with that setup and it works for me great. With as short of a barrel as I have, 300yrds is my max with factory ammo, 400 with my handloads. The few guides that I knowhave no issues with the 308,if it is what you are comfortable with and can shoot accuratley,then it is fine. You know your range limit and what you are comfortable with, so just don't exceed them. And if a guide for a Elk hunt tells you that you have to take a shot over 300 yds, I would find a differant guide, but that's just my opinion. This is not to say that every guide will feel this way, nor that Scirrocos are the best choice, we all know there are plenty of choices out there. Barnes, Nosler Partitions, Hornady Interbonds/SST's, just to name a few. It is really your call. I would however advise against shooting the heavier 30cal bullets(180+gr) that are offered.I know that energy is increased, but ballistic tajectory suffers greatly limiting a 'comfort range'. I hope this helps, and feel free to ask anything else about this subject. Best of luck.

Jerry