I need your help. Can some one compute for me what my Muzzle Velocity would be for a 30 caliber 180 grain SGK with a B.C. of .501 being Chronographed 20 feet from the muzzle. The average speed @ 20 feet from the Chrony is 2775 FPS. Elevation here is around 1,500 Ft. above sea level and temp. was 50 degrees with a humidity around 50 %. This is what my 7.82 Patriot XP is doing and I can't find my old Ballistix software (just moved) that can compute actual MV from whatever distance you have the chronograph set-up at. I'm guessing it is around 2,800 FPS but I want to be as accurate as possible. Thanks!

Ernie

Hey Ernie,

I take the "velocity loss at 100 yards" per ballistic charts/program, divide by 300, and multipy that times distance in feet from the muzzle. A pretty good rule of thumb is that most lose ~300 fps in the first 100 yards, so I figure 1 fps for each foot from the chrono. You're going to be real close to your 2800 number....

Regards,

Bill