Which drag function does Sierra use?

[jimbo88mm]

Im using a ballistic program (Al_Bal) and it has an entry for the drag function. I have noticed that some bullet makers include this with the BC information. Sierras website just list the BC.

The bullets im using are the 70gr and 95gr SMKs.

 

[nhm16]

Sierra uses G1. They give multiple BC's at different velocity ranges for some bullets (e.g. SMK's) to compensate for the fact that those bullets don't correspond very well to the G1 reference bullet profile. The correct solution is to use G7 for long pointy boattails, like SMKs, but for marketing reasons it's not commonly used because G7 numbers are lower.

You should also look into getting Brian Litz's book, Applied Ballistics for Long Range Shooting, which has empirically measured G1 and G7 BCs for lots of bullets.