# Ballistic question

If two bullet shaped objects were traveling through the air at say 2,000 fps. One was .03 diameter and 150 grains, and one was scaled down 10 times in mass and shape. Which would feel the affect of the air more?

The first, larger one since it would have 100 times the frontal area as the smaller one for only 10 times as much weight. It would have a sectional density 10 times lower.

/geometry.

By “scaled down 10 times in mass and shape”, do you mean that the mass was scaled down by a factor of 10, but the density and shape were kept the same, for a reduction in all linear dimensions by a factor of the cube root of 10? Or do you mean that both the mass and all linear dimensions are all scaled down by a factor of 10, for an increase in density of a factor of 100?

In the former case, the smaller bullet would be affected more by air, but in the latter case, the two bullets would be affected approximately equally. What’s relevant here is a quantity called “sectional density”, or mass divided by cross-sectional area. The bigger bullet has more lead behind every square millimeter of surface than the smaller bullet does.

You are on what I am trying to ask. I am not sure how to apply the 10 times scale down to the density index vs size.

Presumably, this should be 0.3". If a bullet made of any known material were 0.03" in diameter and had a mass of 150 grains, it would have some absurd length. To say nothing of the one that’s 10% of this diameter at 15 grains.

Yes .3