There are a wide range of opinions on this one. Some say its estimates are overstable, some say they are underatable. Use whatever works for you. The fact that it does not take velocity, or the range that the bullet is being used at, are two of the problem areas that will evoke some discussion. Modern thought from the BPCR people seem to lean toward spinning bullets faster then Greehill would indicate. Classic schuetzen & Long Range rifles go the other way.  Like I said, Make up your own mind and shoot a few.

  The constant used these days is either 125 or 130. That seems to give the best results over the widest range of calibers.

PETE