I just got back from test firing my 10/17hm2. First shot, I had the rifle up to my shoulder, looking threw the scope, I squeezed the trigger and Bam! I got a face and Arm full of powder and brass! (yes I am left handed). I found the empty case and found that the head had split. This was with CCI ammo, and thinking it may have been a bad round I dropped the rifle down from my face and racked off 4 more rounds. The rifle functioned flawlessly, but everyone of the cases had ruptured. Ok so I load another mag with 5 rounds of Hornady and again all 5 cases ruptured. In the past this rifle has worked great shooting 22lr. It is using a WP 17hm2 barrel with the EBCO mach2 charging handle. only other mods are a VQ extractor and a PC Hammer. What do you guys think I should do? is this a Barrel problem? Is there something I can do to the bolt? I seen another thread where there was a problem with a WP kit. Anyway be very careful when test firing a converted hm2. If I hadn't been wearing glasses I would be at the emergency room right now getting my eye worked on.