Originally Posted by Colorado4Wheel
So now you agree that the Rifle Primers are not sealing and that is causing the problem. Before you didn't. I'm confused. Editing your first post didn't help.
I'm likewise confused. I never disagreed that harder rifle primers could be a cause (i.e. play a part). Even your own reply stated rifle primer hardness "may" be the cause, not "is" the cause. What I believe now, with more data, and with greater certainty, is that the hardness of rifles primers is the cause (i.e. play the
part). Meaning, for example, it's not the brass and not over-pressure. Basically, it's an under-pressure issue inherent in using harder rifle primers in 9mm and .45acp. Also important, at least to me, is that I also now think the older red box CCI SPPM, which are most of the SPPM I've used, are harder (because they are in my experience) and, aside from light primer strikes, can also behave more like rifle primers relative to expansion to gas seal the primer pocket.
Is that not what's said above and in my replies?
I'm a curios fellow. Reloading is a hobby. This may not be news to you (even though your reply stated "may" not "is" in terms of certainty of cause), but, in terms less conjecture supported by actual data, it's news to me as far as certainty goes. I'm sharing as other reloaders may be interested given many condone (as I do) using SPPM, SRP and SRPM in 9mm. My main message is that it works, but you could get gas cutting on your breech regardless of load or brass used. Does not bother me on my high volume Glocks, and I never thought much of it before when getting gas cutting using SPPM in loads I knew were safe. But, it might matter to some, and would matter to me on some other guns I own.
Hope that helps clear things up.