A scientific approach to it when shooting steel plates, the bullets that weren't peeing Harden made a little over 1/2" wide by maybe quarter inch deep impression in the steel plate, bullets that were tumbled harden made a 3/8" wide to a little over 1/2" deep penetration, on the same steel plate. that's why I figured that it made some difference in hardness. this was done 5 times using the same bullet, same load, test was done at 100 yards, steel plate was a 1" thick 4'x4', so the steel was the same for all testing. these bullets have no hollow point or flat tip, tip is like a needle, shot out of a 223 1-7 twist barrel. This wasn't a Laboratory test or test for hardness with a Rockwell tester, this was a Hands-On hands Real World test shooting live animals and steel plates
