One of these Blazer casings is not like the other. The large pistol primer that is crimped behind them tells part of the story.
Lets see whats going on, shall we?
Miked the primer pockets. This is the one that crimped the primer. Then to the other one:
This is the other Blazer casing. It appears that some bean counting dweeb said "Hey, we could cut .002 cents cost out of each round if we went to small pistol primers!"
It does not stop here, apparently at the last bean counter convention the Blazer people told Fiocchi USA and Federal about the amazing cost savings!