We have found that the BLK 300 1-7 and 1-8 twist rate are the best. If you are going to shoot subsonic targets with heavier projectiles, then the 1-8 twist rate is ideal for you. On other hand, if you are into shooting loads that are supersonic and light in weight, then a 1-7 twist rate is well-suited for you.  We have found this with many tests and observations. These are written blindly from another source as we go out into the wild, shoot, hunt, or in short, keep at it. Hence, we learn what we practice and then pen it down here. We hope to have answered this part with clarity based on that at least.