Cheapshooter, Also, where is a denim covered ballistic gel test? That is the common protocol for performance testing of bullets. Kinda think they have a reason for not doing one.
Here's a couple of links for test of 9mm in Gelatin.
http://www.best9mm.com/9mmballistics.html
http://www.firearmstactical.com/ammo_data/9mm.htm
http://mousegunaddict.blogspot.com/2012/05/ballistics-testing-remington-umc-9mm.html
And these are just a sampling of the many different tests, which include several layers of denim. Enjoy, and I hope this answers your question.