E-Factor

[Ronin84]

I've been away from my books for a bit and I don't remember how calculate E factor for weapons that are not in the rules. Help

I know it had to do with muzzle velocity and bullet dia / 50 I think but I'm not sure. IF someone could even point me to where it's at in the books...I would appreciate it!

Thanks in advance

Ronin84

[mmartin798]

In 4th ed, it's on page 92:

(D*V)/50 = E

where D= Projectile diameter in inches, V=Velocity at launch (muzzle velocity) in feet per second, E=E-Factor

For metric

(D*V)/387 = E

where D is mm, V is m/s, E=E-Factor