I think if you are going to build a 338 snipetac you should consider a faster twist rate if you are spending the money on a rifle chambered in this or any other cheytac derivative's. You can shoot jacketed bullets out of these rifles but I don't see the purpose in it in my experience. This rifles performance begins past 1000 yards and is the reasoning in having a faster twist rate barrel which will keep the RPM's up and your bullet more stable at the distances that it is purpose built for. Cutting Edge makes some well suited bullets for the 338 ST. Kirby Allen, David Vires, Bruce Baer and Joel Russo are some great resources and have years of experience on this cartridge. They have all ready gone down the rocky road of development, and have lots of helpful information. Contact Bartlein barrels for the size, contour, and twist you need. They mad the last one I had build, 1.4" for 6inches, then straight taper to 1.1 at 26" and a quick step taper to 30". All the best with your build.