Bullet Jacket Scratches can affect BC and long range accuracy

Bryan Litz shares a clever tip on how damage to the bullet jacket can affect the Ballistic Coefficient of a projectile. This tip was posted on Bryan Litz Ballistics’ new Facebook page. Subscribe to the page to get Bryan’s most recent posts.
Bryan says: “If you scratch the bullet case when you seat it, this can cause the BC (bullet casing) to be inconsistent. This shows up as vertical scattering at long range.”
We see this when we run Doppler radar for competitors at Applied Ballistics Mobile Lab. If someone is shooting a shot that has a BC that is usually very consistent (1% or less), but they are seeing a higher BC variance, it could be due to the bullets having been damaged during the loading process.
The photo in the lead shows a badly scratched jacket of a bullet sitting inside a case with a rough mouth. To avoid such jacket damage, it is important to chamfer, deburr and smooth casemouths after trimming.
Below is an example of a Doppler Radar result that shows excessive BC variation. Such variations can increase vertical dispersion when viewed from a distance. This can lead to larger groups and lower scores.