Hi there:
it definately sounds like a gas pressure issue to me, I have an XCR-l with no troubles (sorry) but I have an 8mm FN49 and when i first started shooting it, it would pull the extractor right through the brass almost every shot it drove me nuts because i thought i was going to reload for it, but anyways, i did a bit of reading and found the gas setting was cranked way to high and was pulling the case away from the chamber before the pressure subsided and the case shrank, so sure enough i started to dial it down and now it leaves absolutely no mark and throws them in a nice neat little pile just off and to the front of me so that one is easy to try for you give it a go
cheers, Steve