So, a year ago I purchased a Mossberg 4x4 300 Win Mag rifle. I know, I know, cheap rifle. I have fired it a lot and done a few load developments with various powders and bullets. It does okay at 200 yards (within 1 MOA) but beyond that I get pretty wild results. Wild enough that I don't feel confident using it for hunting. I would say at best the barrel is a #1 contour and for a magnum rifle that's crap, I know. My reasoning for the wildness beyond 200 yd though is barrel whip. Here is my theory and for which I would like some feedback. The heavier grain bullets I have been shooting (nothing less than 175 gr) and the high pressures needed to push these rounds down range at velocities of 3,000 fps or better are contributing to barrel whip and thus the erratic rounds at 300 yd or further. My theory is to drop the bullet weight to 150 gr or below to minimize the barrel whip. I plan on doing a load development on a 150 gr bullet and see what happens. Any thoughts on my theory?