Originally Posted by Rickyrebar
300WSM Nosler BST 180 / W760 Powder
Your rifle is acting just like the Nosler manual says it will. The most accurate load for that bullet with that powder is the lightest load. It doesn't always work out like that, but it did this time. The good news is you know at least one load that shoots tiny groups. You "really" need to know how fast it's going.
None of the powders listed for that set of bullets are most accurate at max load.
What to do next:
1) You might try Viht N550, the manual says that powder was the most accurate with a max charge (but still start low and work up).
2) You might ask here for loads folks use with that bullet.
Basically what you do next is try a different powder.
Beyond that, the very next addition to your reloading equipment list should be a chronograph. I have a CED. Like it a lot. With out knowing the velocity you are not going to be able to do any sort of ballistic projections or even reasonable calculations of point blank range based on data. Fantasizing about velocity and then doing ballistic calculations is complete a waste of time.