Re: 5R mil-spec
I'll be moving to CO Springs here in January, and have a 5r in 300wm. I'm assuming your 308 is a 5r? and you're looking for a 5r in 300wm?
I believe the twist in your 308 is kinda non-standard (11 1/4 if I remember correctly) so it can handle the 168 and 180 slugs, but don't have the specs in front of me. With the 300/5r you'll have a 1 in 10 and no problems stabilizing up to and past 210, and I believe even 230.
I'm currently trying to work up a load in my 300wm 5r, didn't have much success with a newer powder, Magpro (but fantastic velicities) so I'm going with one of the standbys for caliber: H4831sc. That should get me going for next season with all summer to practice.
From what I've seen so far, I can't get mine to shoot decidedly better than a moa, but it consistently shoots right at with the cheapest factory ammo out there. Sometimes a tad more, sometimes a tad less. I'm hoping a good load workup can bring it consistently under, so I can push my max out a little further.
I just wish it was as much of a tack driver as the 308 5r's.
Good luck and keep us posted!