That's.... geez... you could do that with a slingshot.
I suspect those bullets aren't very concentric, the rather large variance in length is one clue... besides being "seconds".... and 1:8 is a rather fast twist for 55gr bullets, even extra long ones.
I'm pretty sure you're spinning them too fast. They might work just fine in a 1:12 or 14 barrel but not so much at 8.