I understand that reloaders sometimes have a problem in removing the primers simply because the Bren striker bells them out and the ejector stakes them in with a distinct chisel action too. Originally to prevent the 'caps-out' problem the plagued the early trials. Just a couple of loose caps could stop the Bren.

If the gas it too high and the ejection harsh it can cause the spent cases to beat hard against the rear of the ejection slot in the piston extension and then beat down hard on the ground, denting the side of the case and neck.

But on the bright side, reloading and all that palava shpould be the last thing on your mind when you're shooting a Bren