Back when 9mm ammo was super cheap (Like $5 a box), I didn't bother reloading for 9mm, and just shot whatever was the cheapest.
I shot case after case of the blazer 9mm ammo, because it shot good, and was cheap from big box stores, and my LGS would give me a sweet case discount.
I had 2 case failures in total, both case splits, 2 different days.
Stopped buying blazer in 9mm after the first split, shopped shooting it after the 2nd. Gave the few boxes I had left away (With warnings) to a friend. He shot it zero issues.
1 failure was in a cz75b (The narrow ejection port took most of it.), the other in a S&W 5904. (I took a bit of burning soot to the face-wear your shooting glasses!).
One case split between 1/3 and 1/2 way down (Looked like the typical split, started at the neck.), was a little loud and spit a little hot powder at me. The other split almost all the way down and looked like the split originated just above the case head, not the neck. There was a round burn mark just above the case head, then a split almost all the way to the neck, but stopped just shy of the neck. Maybe a void in the case head? It was so loud I thought the gun blew up. Never had a failure of any other type with blazer ammo.
I switched to Win white box. It didn't shoot as good, but zero failures. It also gave me good brass to save for loading later. I was so disappointed in the way the win bulk 100 pack shot, I started loading for 9mm after less than 10 boxes. The blazer really shot well.
Never heard of any other failures like it.
Never a failure in any other caliber I tried, not 10mm, not .44 mag, not .45 acp not .45 colt. Didn't try it in .40, just felt like asking for trouble.
I bought a couple of cases of blazer aluminum in 10mm and still shoot it (One of my guns chews normal brass, but ejects this perfectly.) It was about $9.00 a box by the case-that's how old it is.
Maybe I got a bad batch?