Link to video of test


Fiocchi 55 gr PSP fired from 16" and 11.5" AR pattern rifles into calibrated 10% gelatin. Both rifles are 1:9" twist rates and both had a Surefire FA556AR attached.

BB calibration: 596.1 fps, 3.7"

16" barrel results:

Impact velocity: 2,951 fps
Penetration: 12.3"
Retained weight: 28.0 gr
Max expansion: 0.493"
Min expansion: 0.315"





11.5" barrel results:

Impact velocity: 2,572 fps
Penetration: 11.6"
Retained weight: 36.1 gr
Max expansion: 0.483"
Min expansion: 0.382"



Some fragments I strained from the gelatin:





Using Hornady's online ballistic calculator and the BC for a Hornady 55 gr soft point (I can't find the BC for this bullet), the 11.5" numbers represent what you should see at about 100 yards from a 16" rifle.