Some years ago several of us were doing a lot of bullet testing in the wax of The Test Tube, a fine product that failed on the market due to underfunding by the major backer. Bullets left a permanent "wound cavity" inside the tube, and the spin of the bullet was obvious in the cavity.
The most curious aspect was with TSX's the rate of spin in the cavity increased as the bullet penetrated deeper, but in the cavity from standard bullets the rate of spin remained the same throughout. In fact, with most bullets you could measure a complete turn in the cavity, and it would perfectly match the rifling twist of the barrel it was fired from: If the barrel's twist was 1-10, then the bullet would spin one turn in 10" inside the wax. But if the bullet was a TSX (or any other "petal" type bullet) the rate of spin increased throughout the wound channel.
One of us thought this might be due to the "propeller" effect of the petals, since in an expanded TSX they're typically slightly tilted like the blades of a propeller.
“Montana seems to me to be what a small boy would think Texas is like from hearing Texans.” John Steinbeck
