That appears to be a case rupture from premature ignition, correct? As in the cartridge was not fully chambered before the primer was struck. I think the case wouldn't have unfolded like that if the rupture occured in the chamber.
If so, it is more a fault of the firearm than the case material. Brass cartridges will rupture exactly like that.
From what I remember, CCI didn't recommend the use of aluminum cased Blazer in certain (Marlin?) lever action rifles due to their extractor design. It had nothing to do with kabooms.
I believe that CCI also changed their aluminum alloy several years ago to reduce "sticking" issues in revolvers.
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