I have been serious backpack hunting for 35 years and after this past season am reconsidering my rifle. I have always packed a 12-14 pound long range rifle built on a wby mk 5 action which is heavy. For years now it has been a 338-378 wby. Early on hunting/guiding only after seeing 50 or so elk shot I realized the smaller calibers were definitely not made for big elk. So I switched from the 7mm/300 wby class and everything else small caliber necked off the standard magnums and carried the big heavy rifle. I am a big guy at 6'3" 220 and it just didn't bother me until age caught up with me.
So now I am rethinking this thing again to shave several pounds off my rifle I have got to shave a few hundred yards off my range. The overbore magnums all need barrel length or suffer greatly so I am looking again at the larger calibers where barrel length has less effect. Rethinking all the hunting through the years most times I could cut the range to 650 or so yards. So I'm looking at that range and a light rifle. The short mags on a short action with a 26" barrel look good to me. There are getting to be better 8mm bullets and that one wouldn't lose much in velocity or just necking a 8mm to 338 for the better bullets. I figure by next year they will offer a 338 if they don't already have one. I haven't looked so I don't know.
Also I could easily shoot this one without a brake so that would also help a little. I have seen some amazing shots with the 338 win mag through the years if I wanted to lengthen the action a little over the short mag. I have a super trophy backpack deer area and thinking about necking the short mag to 264 and take advantage of some super BC bullets in that caliber. I had a friend years ago who had good success with the 300 wby necked to 264 years ago until he tried it on elk. I think for deer it or the high BC 7mm bullets might be a good one.
Keep us advised as you research this thing. I am looking to. I have about a hundred custom rifles
in about any popular wildcat you could imagine but the short mag stuff wasn't around when I did all of those. I have had great luck with the Gibbs line and they will virtually equal the standard magnums performance but still that is a standard action based off the '06 case. Weighs a few more ounces than the short action.