I think that the scope is a likely culprit. I did the same thing w/ my 300WM, the reticles broke loose. Every shot moves the reticles so the point of impact changes EACH SHOT. My wife (usually a great shot ) missed several shots in a row on a cow elk. I started to "encourage her" and she finally shoved me the rifle and told me to try. After several misses I finally got lucky and dropped the cow. Long story short only use top scopes on the magnums. I agree w/ JamesB the 180gr are the way to go w/ the 300WM. One load for all occasions.