500 meter rams vs 50 cal. prb's.....

[longcruise]

What did you use for a BC? Its under .07 according to Lyman.

I used .056. Hard to tell what accuracy these ballistics programs have for round balls.

Ballistic 4.13 documentation give a formula for deriving a BC for use in the British Round Ball Table. When I run it through 4.13, the .50 caliber ball zeroed at 100 yards has a drop of 72 feet at 550 yards with a starting velocity of 1900 fps. 1900 fps is the maximum velocity useable in the British Round Ball Table.

 

[rawdog]

According to a ballistics program using the GS drag curve for roundballs and a ballistic coefficient of .104 for the 176 grain .490cal ball and assuming a 100yard zero with 1750fps muzzle velocity:

The drop at 500yards is 67.5 feet and the remaining velocity is 309fps.

The drop at 300yards is 11.25feet and the remaining velocity is 534fps.

YHS,
rawdog

PS - the usual ballistics coefficient you see is for the G1 drag curve, most commonly used, but is for conicals and not round balls and is not accurate over all velocities, ie, small errors when used for PRB. GS is exactly for roundballs and due to a different magnitude peak will also have a different magnitude of ballistic coefficient.