6.5 cartridge bullet seating depth for magazine feeding

[justeric]

I have a Savage 10 FCP - K in 308. I have a 10 round magazine for the gun. I want to put a new barrel on the gun in one of these calibers:

6.5 x 47
6.5 x 47 LR
Creedmore
260
260 Improved 30

I want to take advantage of the better BC with the long bullets in these calibers over my 308. My concern is that I will either have to seat my bullets inside my case (past the neck) or use smaller lower BC bullets if I want to shot the cartridge from a magazine.

Does anyone know which of the cartridges above will shoot well from a magazine without worrying about seating the high BC bullets into the case?

My intended purpose for the gun will be tactical matches out to 1000 yards.

Thanks,
Eric

 

[IndispensableDestiny]

Your first step is to measure the maximum cartridge length the magazine will hold.