Ballistic Protection standards reference

[Milano]

If I may add my 2 cents what is the difference between a 17 HMR traveling at 1300 f/s and a 338 Lapua Mag at 1300 f/s? Sectional Density. Instead of a straight look at the velocity I made up a formula that works fairly well. It is:

(1000/{speed in M/S}) x (Sectional Density) x (1.5325)

For example:

17 HMR 20 gr @ 1300 f/s -- DAM 1 PEN 3

.338 Lapua Mag 250 gr @ 1300 f/s -- DAM 4 PEN 3

(As an apples to apples comparison: the 17 is at 250 yards to drop to 1,300 f/s. The Lapua is at 1,285 yards to slow down to 1,300 f/s!!

Anyway I made an excel spreadsheet that makes all this fairly easy to figure out. Any question about how it works please ask. Here is the download: