Re: Moving up from .308 to a 300 WIN MAG.
Nothing wrong with the 300 WM if you need all of that energy. The recoil is easy to tame with a good break, however, the barrel gets red hot after 6 to 8 rounds. The barrel life is shorter if shooting long strings. The cost to shoot it is more. As for loading lighter for it, I would think that this would defeat the purpose of having a 300 WM. Besides, once you have your load, and write up a card for your rifle, you pretty much have to use it. Use a handicap 300 WM, while the guy next to you blows by you with a hot 260??? Not me.
By now you think I don't like the 300 WM. Not true, I have one, but unless I'm going somewhere that I can shoot at long ranges, at a slow pace, it stays in the safe. I also have had the parts for a 338 LM for over 2 years, and I haven't build it yet because I just don't have a place worthy of burning that kind of powder.
I honestly like the 6.5 calibers, and the good old 308 for most of my shooting. The Creedmore is my favorite of all, and the 260 right behind it. I have the 6.5x47 Lapua also, but will soon sell it to make a little room.
Remember, these are my personal thoughts only, and I'm by no means an expert. I'm only tring to share what I have experienced with what I have.
Best of luck.