I need help find my down range trajetory and velocity? I loaded a tack driver load of 95grs of IMR 4831 in my 30-378 wby 165 nosler ballistic tips. and is sighted in 3.5 high at 100 yards and bullet hits 16 inches low at 430 yards. how fast is my gun going cause I have no way to figure it out? also if anybody knows any good loads for 165gr bullets in this gun let me know.

If you can tell me the ballistic coefficient of the bullet you are using (maybe from the manufacturer)and the height of your scope or sights above the centerline, I can tell you how to get a rough idea of your muzzle velocity by using any of the ballistic programs available.

To really do it right, however, you need a chronograph to actually measure the velocity.

I went ahead and made some assumptions.

If your scope is 1 inch above bore centerline, and you are using a 165 grain ballistic tip Nosler with a BC of .475(from their website), to have the bullet 3.5 inches high at 100 yards and 16 inches low at 430 yards, you'd have to have a muzzle velocity of 3050 feet per second and be zeroed in at 285 yards.

This comes from the Norma ballistic calculator on their website.

This velocity should be regarded as very approximate. I cannot vouch for the accuracy of the Norma ballistic calculator since I've only used it for trajectory calculations under 150 yards.

A safer assumption would be for the scope to be 2" above the centerline of the bore. The old Lyman Alaskans, Weaver 330s etc were 1.5", and new scopes have to be higher due to the objective bells.

You actually already have the more important figures which is where is your bullet hitting at various distances. If the load is not showing pressure signs and is within published loads, the points of impact at various ranges are more important than the velocity.