Thread: 223 case defect

Any ideas what causes the defect shown here on the left?


A bloke at the range today was firing new ppu in 223, Winchester and some reloads.

The extracted cases had a pronounced rounded shoulder and the concentric lines around the shoulder.

The ppu cartridges gave a lot of resistance when closing the bolt.

Some of the other cases were also hard to extract.

Cheers
Pete