Re: 6mm 105 and 107 velocity debate. How fast can they be pushed.
The answer to your question depends on a number a factors including the actual vs quoted rate of twist, and the depth of rifling. Some barrel manufacturers don't hold tight tolerances for twist. For example, I have Shilen 1:8T 6-284 that will not stabilize anything longer than the 107MK. Obviously other members and evidently Krieger have had different results. For a better explaination of this read the article on Barlein barrels in the February edition of Precisionshooting.com Also, fewer lands usually means deeper lands which in turn results in a deeper engraved bullet. Some shooter believe that the depth of bullet engraving has a lot to do with the maximum velocity that a bullet can be shot without coming apart. Therefore when comparing the experience of fellow shooters it is important to take into consideration whether they are really using the same equipment or just the same caliber. I have never shot a Krieger, but if they are telling you their barrel will shoot 107MK then that's the advice I would follow.
BTW, I'd make sure the barrel you order also shoots the DTACs. If you don't get the velocity/accuracy combination you want with the 107's, you may wish to shoot the DTAC's and enjoy less drift rather than simply downloading the 107's. Although I have not run the ballistics, I suspect that the velocity advantage of the 107's vs 115's at 1K is marginal, and the terminal difference non-existent. I would tend to think that what matters most is hitting the target, and its alot easier to estimate the come-up than it is drift.