Virtually all custom actions can be got in a left bolt configuration. I must be honest with you.... as a right handed prone shooter, I would LOVE to have a leftie action. It makes so much sense to me to keep your dominant hand welded and keep your eye reielf consistent while your non-dominant hand cycles the action. To me, you lefties have the best of all worlds! As to caliber, there is no right or wrong answer. CyaN1de proved last weekend that a good shooter with a 6mmBR can still put 6.5, 6.8 and 7mm shooters to shame at 900M. Likewise a goot shooter using slow, mediocre 30 cal bullets can whoop 223's with velocity and good ballistics. It all boils down to the shooter. I would stay away from a 300WM, because the ballistics of most 30 cal bullets sucks. The 6.5 Swede is a great choice, and so is the venerable 260 Remington. In F-Class, the trend has swung towards heavy 7mm bullets, but a 6.5 (or even a 6mm) in the hands of a good shooter can kick the butt of a mediocre 7mm shooter any day. Heavy recoil is not at all desirable in long range precision shooting.