I have a Marlin 717 hm2 that had a round blow back through the rim. It set off the next round in the clip and cracked the stock in two places, broke the trigger guard and ended up with the bullet in the barrel. I sent it back to Marlin and received it today supposedly fixed and tested. I took it right to the range and fired the first shot, no problem. The next shot split the rim and blew back through the bolt area splattering residue in my face. Well, it's going back to the factory, AGAIN! I started looking at the CCI amo and discovered some split necks in some spent casings. Also, I found that with slight pressure, I mean slight, the bullet would slip right into the case. Yikes! This is the first thread that I have been able to find on the 17 hm2 problem so I wanted to share what I am going through with it. I am hoping the factory will check things out closely like the issues in this thread. In the mean time I am going to contact CCI and get rid of the rest of the ammo with the same batch number. Looks like Eley may be the best 17 hm2 so I will give that a try when the gun gets back to me.