Help me pick a caliber for a magnum length Mark V

[TaperPin]

If you go with a 7 mag over the 7 prc, the saami chamber is much more sloppy, which is why the prc calibers all shoot well. You can have a custom reamer made that improves on the normal saami dimensions.

 

[wind gypsy]

7 PRC. 28 nosler if one thinks they need to go crazy fast. Other than current factory ammo options, i don't see a single upside to a 7RM over a PRC.

On a custom barrel, the only thing a 6.5-300 weatherby has going for it over a 26 nosler is some people think the weatherby name is cool. Any performance improvements the weatherby has over the nosler is due to a longer throat or more pressure, neither of which matter on an aftermarket barrel where the throat can be spec'd and which will be handloaded for. But with the weatherby you'd get the luxury of paying more for lesser brass that comes with a belt. Still, I think frank green of bartlein summed em up well with how the 26 nosler was referred to as 26 why and 26 stupid in industry circles.

 

[robtattoo]

.460 Weatherby.
Always go bigger!

 

[Flyjunky]

If you're stuck on a 7mm then I'd probably go prc.

Do you have a bullet in mind or an idea on what you'd like to accomplish ballistically? Personally I'd go for something a little lighter like a 6.5prc. It will have less recoil and like said above a 147eldm or 156 Berger are outstanding long range bullets. You already have a big hammer for bullets in the 215-245 class, so why not get something that's a little more fun/easier to shoot?