Strange lines on 5.56 LC brass

[76_bronco]

I purchased a few hundred rounds of (supposably) once fired LC 5.56 brass a couple weeks ago. Turns out that about 1/3 of it had been reloaded, so while working up the stuff that wasn't once fired for coyote hunting, I ran across a few pieces like the one in the pic below. Any idea what caused the axial lines that run half way down the case? I don't plan on loading them, but just curious as to what caused the lines. it's an LC 09 without the nato cross.

Thank's Greg

 

[alsask]

HK fluted chambers will cause that. They are OK for reloading.

 

[pistolero guy]

strange lines

edited to ditto what alsask said

 

[76_bronco]

Now that was a fast answer, thanks guys!