1911 magazines can be fickle things. (Maybe
that's the "feminine" part of these guns.
)
The compact variants, seemingly more so than full sized counterparts and their magazines. One classic example I had was a Colt Defender that ran just fine with every six or seven flush-fit mag, EXCEPT for the one that came with the gun. It also did fine with the longer, Government model magazines, regardless of brand. Never did figure that out.