I have a 90s vintage Springfield "Mil-Spec". It will take anything ".45 auto" I can fit in the factory 7rnd magazine.

Sometime in the late 90s I bought a 4-pack of Chip McCormick 8rnd magazines from SG. Two of them work great, two of them FTF consistently (100%). You can even feel a difference when you snap them into place in the mag well -- they take a bit more effort to push in the last few mm before the mag release snaps in.

I contacted CMC directly, sent them the mags, they measured and sent them back, "all good, everything measures as it should."

Still a mystery. They're tossed in a parts bin somewhere with a toetag that says "unusable."