I've been reloading since the mid-90's and never had a case head separation until recently. One six months ago and 3 in the last month. Has occurred in 2 guns ( HK P7M10 with 100,000+ rounds and P7M10 with <2,000 ) so I don't think the problem is with the gun. My load is light and I haven't changed it in over 10 years. I have used a Casepro for the last 3 years to roll size the brass before reloading. I have my suspicion of the cause but would like to hear other ideas to make sure I'm not overlooking something.
Also, I know the HK P7M8 (9mm) runs without an extractor - even HK says it will. The extractors on my P7M10's were blown out when the case separated - they're in the grass never to be seen again (even a magnet didn't find them). The P7M10 won't run reliably even with factory ammo. Any ideas on getting my P7M10 to run without an extractor?