Question on Lyman manual

[Dewey 68]

I recently purchased the 49th edition of Lyman's reloading manual. When viewing the load data for each caliber, there are two numbers off to the right next to each bullet weight, one I think is SD, the other may be HD (I don't have it in front of me). I've searched through the thing and I can't find a legend for what these numbers mean.

Does anyone know?

Thanks!

 

[Ol` Joe]

BC & SD - Ballistic Coefficient and Sectional Density, both are measures of how a given bullet "should" perform in flight and terminally. The higher the number the better in most cases and they roughly go hand in hand.

 

[Dewey 68]

Thanks much Joe!