Do Ballistic Coefficients change with velocity?

[Earl]

Does a pellet have the same Ballistic Coefficient at 600 fps as it does at 950 fps?

[ballisticboy]

It should if the correct reference drag law has been used. In practice a suitable reference drag law is rarely available for all speeds which, coupled with poor test and analysis techniques, produces BC's which vary with speed. Any variation should only be small unless an entirely unsuitable reference drag law has been used, as they often are.