VIRGEL is a "heuristic calculator" designed to give quick and dirty estimates of the likely terminal performance of self-defense ammunition for most handguns as well as some rifles and shotguns.
VIRGEL cannot tell you exactly how your ammunition will perform. But it can give you a better idea of how bullet nose shape, diameter, weight, and velocity interact to determine pentration and wound mass.
Because VIRGEL isn't really gelatin, it has limitations. For example, VIRGEL can't predict bullet expansion or deal with tumbling, fragmenting, or very high velocity bullets. But VIRGEL is faster and cheaper than real gelatin and fits in your phone.
VIRGEL estimates penetration using a simplified "THOR" equation (see chapter 9 of Quantitative Ammunition Selection by Charles Schwartz) fitted to data from Duncan MacPherson's penetration modeling (see MacPherson's Bullet Penetration, ch. 10).
VIRGEL calculates "Defense Wound Mass" using MacPherson's "Wound Trauma Incapacitation" model, discounting the last 3" of bullet penetration as too slow and penetration beyond 15" as too late.
VIRGEL calculates "Big Game Wound Mass" using the full depth of estimated bullet penetration.
VIRGEL calculates kinetic energy as a possible indicator of barrier penetration and power factor as an indicator of recoil.
VIRGEL is intended as a heuristic tool and makes no wild claims for accuracy beyond (maybe) two significant figures. So, don't fret over not nailing velocity to the last ft/s or weight to the last grain.
VIRGEL was coded by Robert Webster and Ross Kowalski in their copious free time and is licensed under MIT's open source initiative "Approved License." (C) 2022, R.E.Webster.
/100"
gr
f/s
10% Gel Penetration: inches
Defense Wound Mass: grams
Big Game Wound Mass: grams
Kinetic Energy: ft-lb
Power Factor:
10% Gel Penetration: inches
Defense Wound Mass: grams
Big Game Wound Mass: grams
Kinetic Energy: ft-lb
Power Factor: