I can attest that a 300 grain 50 cal ML bullet at 1400 ft/sec will be thoroughly be deflected by a 1/8 inch twig at 50 yards causing a complete miss at a deer 75 yards away.
I found this sight some time ago and love it.
Here is a deflection test they conducted-- enjoy all the other stuff also
http://www.theboxotruth.com/docs/bot40.htm