E-Factor
 

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

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