Thread: 6.5 Creedmoor

Sectional density is interesting in that a projectiles SD is only accurate prior to impacting a target and deforming. As soon as it deforms the SD reduces. SD being a measure of projectile diameter vs projectile weight. Diameter increases as a projectile deforms, weight reduces or stays the same and so SD reduces.
Saying one projectile or caliber will penetrate better than another due to its SD is only possible when using non-expanding projectiles.