"He is starting to get into hunting out here in Colorado and beginning to realize that mountain hunting is a tough game."
You don't mention his experience in hunting/shooting prior to moving(?) to Colorado. Unless he has shot a 300 WM a bit and is comfortable with the recoil and thinks he can handle the increased recoil of an even lighter rifle in 300 WM... I would look at the oft mentioned alternatives; 30-06, 308, & 7-08.
I HAD a 6.1 pound 300 WM (bare rifle weight) and really liked the combination, but the recoil was quite snappy and after several years asked myself why deal with the unnecessary recoil when an '06, or 308 would suffice for everything I need to do (Deer, Elk & Bear). I enjoy shooting them a hell of a lot more, hence find myself at the range playing with them more than I ever shot my 300 WM.
YMMV
Jerry
I like this and what Captain Craig said, too. The 300 Win Mag is an excellent elk cartridge(maybe one of the best), but no one can run fast enough to give me one weighing 6 pounds, or even 7 for that matter....BTDT a couple of times.
It can be done of course but I have seen more moderately experienced shooters wither under the recoil effects of a lightweight 300 magnum, and shoot so poorly with such rifles they might as well have stayed home and saved their money.
The same guys did far better with a 7 pound 270, shooting it accurately and easily. So, for me a 300 magnum had better weigh no less than 8 pounds, all up,and 8.5 pounds is what my old 300 Win Mag weighed. I killed a lot of everything with that rifle.Would not want it lighter, then or now.
Light weight 300's are for hardened and seasoned riflemen, inured to the effects of recoil by thousands of rounds of CF ammo annually,not for beginners.
In the 6-7 pound range, I like the standard cartridges(270-280 etc) and consider the various 7mm magnums the practical upper limit in a 7-7.5 pound rifle....I have a pair that weigh just under 8 pounds all up (I have had several of these over the years),and really would not want one lighter.
They have killed elk up to almost 10,000 feet for me, so I guess they fall under the Mountain Rifle category.
Today my top three picks in factory rifles would be a Win M70 FW (or EW), a Ruger Hawkeye, or a Kimber Montana.
Cartridge? Take your pick.