It appears that for some reason, the Power Belts are not being spun sufficiently to fly point-on from your barrel. They are on the ragged edge of stability. It is possible that your twist is too fast, the grooves too shallow, or the bullet is not being swaged up enough on firing to take the rifling like it should. I am using the Power Belts in a .45 and a .50 caliber rifle, both of which have slow, round ball twist rifling, and these shoot Maxi Balls (370 grain .50's and 240 grain .45's) and Power Belts pretty well. I use the 295-gr. .50 and the 275-gr .45's in my rifles.

Keep yore powder dry!!