Why is it doing this?

[KDX]

I reloaded some 5.56 brass that I had pulled some bullets from (I loaded 23.5gr Benchmark and 53gr Hornady Match HP) and I was looking at the brass and it looks a bit different than the Winchester 45gr CXP1 that I had fired out of the gun. I took a pic and it might be hard to see but there is more 'blow back' on two sides of the neck of the reloads than there is on the factory Winchester rounds. Is this something I should be concerned about?

Not the greatest pic, but the reloads are on the left and the factory shells are on the right.

 

[Cocked&Locked]

If your load is at the light end of the scale, or is a low pressure powder, it may not be expanding the cases enough to seal the chamber, so some soot blows back around them.

 

[agilent_one]

Generally, 5.56 brass is made a little thicker than commercial .223, ergo - it won't grow as much in the chamber, especially w/ low pressure loads.

 

[Ranger]

I was wondering the same thing, I reload 270win with IMR 4350 and I get the same thing. I am loading close to max load so I don't know what is causing this but accuracy seem to be fine.

 

[Levi Garrett]

Pump up the volume

 

[Proutfoo]

one more for insufficient neck seal due to lower pressure.

do the primers re-seat in the pockets properly?