Geetwo,
Help me understand your test. It seems that you are torquing the screw in the mounted rivnet to see when it will fail/stripout, is this the case?
Considering that the recommended torque for a typical 10X32 screw application is in the 30 In Lbs range, reaching from 48 to 80 In Lbs in most of the material is fairly impressive.
http://www.federalscrewproducts.com/torque-chart.htm