Because bullet spin slows down VERY slowly, while velocity slows down pretty rapidly.
A bullet started at 2000 fps from a 1-12 twist is spinning at 120,000 rpm when it hits something near to the muzzle, say some test media meant to see how much the bullet will expand downrange.
A bullet started at 3000 fps from a 1-12 twist starts at 180,000 rpm, and is still spinning almost that fast when it hits something out where velocity has dropped to 2000 fps.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
