Getting different velocities than what chrono says?

D_Lamz

Sergeant
Full Member
Minuteman
Sep 6, 2007
607
366
Central Texas
My 308 load is a 168gr hornady with 43.4gr of 4064 in a hornady case. Rifle has 22in bartlein tube. My velocity I'm getting out of my ProChrono is 2592fps, using the shooter app it says I need 5 mils. I was shooting and had to adjust to 4.4 mils to hit my target. Using the shooter app's velocity estimater, it gave me 2760 at the muzzle. What is going on?!

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