No.4 MKI * magazine adjustment, not feed lips

[browningautorifle]

The front “spring” that folds over the lip of the magazine is still present, and overall the magazine arrived in like-new condition.

Is the auxiliary spring present

Yes...it is. One thing about these "New" mags that some won't get is they may not be as new. We used to repark mags that came to hand or bead blast and blue, I forget... Then they sold in "As new condition" and you couldn't tell.

[Brian Dick]

Oops, I missed that Jim.

Try replacing the mag catch sear spring as Cinders suggests.

[Daan Kemp]

A light press in a vice might just add that smidgen of length. Use might have widened the magazine just that much to make it loose.