I did a home test to test the theory that over crimping actually decreases the case-bullet connection. I made two groups of cartridges, normal and super hard crimp, then I chambered them multiple times in a pistol and measured the change in COL. A I made 3 rounds with my normal 9mm crimp, once fired Speer brass, 124 grain Xtreme plated bullets, all 1.153" COLs. This is group A. Case mouths all measured .377" D I turned the crimp die down a FULL turn. Made 3 more rounds. This is group D. D's COLs were less consistent, at 1.155, 1.156, and 1.154. Case mouths measured .366, .366, and .365". I then chambered all of the rounds 4 times at approximately 0° (A marking), 180° (B marking), 90° (C marking), and 270° (D marking) (so that the bullet hit the feed ramp at evenly distributed angles) using the slide release, then measured them. I chambered all rounds four more times as above and measured again. Notice that the COLs are actually getting a little longer in the group D cartridges. This may be due (in part) to peening the bullet nose and making it sharper. Not sure. Afterwards I pulled the bullets. 1,2,3 are in group A. 4,5,6 are in group D. It took two decent whacks to pull the group D bullets with the impact puller. The group A bullets all came apart with one decent whack. Conclusion: In this test, a "much heavier than normal" crimp significantly increased the strength of the bullet-case connection. Group D bullets resisted setback and the COL actually increased slightly, the cause of which is uncertain. Group A bullets set back in a predictable fashion.