Biff, I'd have to call it a very rare occurrence, given that I've never seen or heard of it over the years. I don't doubt that it CAN happen, but I wouldn't worry about it.
When "high primers" and "spherical powder" are mentioned, that's nowhere near a common situation. Not with any factory ammo I've seen, anyway.
I've only shot GI and Federal ammo in my Carbine.
You're from BATFE? Come right in! I use all your fine products!