When I was going for Dan's 200,000 RPM contest, I got three successive groups of 1 1/4" to 1 3/4" groups. That was with a Lyman 311440HP mold at 2790 fps. That's 200,000 RPM. But I was not down to Dan's 1" requirement, so I lost.
But I have shot jacketed groups at that velocity that on average were not much better either. That is a factory mold in a factory gun and the holes were round with no do hickeys, tails, and none of the bullets bent or boomeranged back to me either. Does that mean it won't happen to some people? No. Just find out why.
Again: If one guy can do it, then there is a logical reason for any limitation. You have two choices. Ask why, and seek the answer. Or be happy with life and stare at the RPM chart.
Neither choice is wrong.