Black Residue on outside of Cases?

[koli]

First time reloading.
Last night loaded 10 cartridges.

.243 winchester

70 grain Nosler Ballistic Tip Bullets

36.0 grains IMR 4895

New Winchester Brass-Full length resized

cci large rifle primers

OAL 2.659-2.662

Shot today.  All body parts intact  :-)

Now to the question:

Last 3 or 4 cases came out of the rifle with black residue on the neck and shoulders.

Any ideas as to the cause of this?

Thanks
koli

[KN]

Burnt powder. Thats not unusual. Its caused by gasses blowing back around the neck. It also meanes your case necks are not expanding enough to seal it off. It happens a lot in light loads. Some callibers are more inclined to do it than others. Nothing to wory about.   KN

[ricciardelli]

You're shooting a light load and what you are seeing are the byproducts of combustion being blown past the case necks.

Up your charge...

[koli]

Understood.

Will be increasing the charge.

Thanks for the input.
koli