If the grip safety is unmodified, more than likely you need more spring tension. Remove leaf spring and bend the grip safety side (far right) of the leaf spring towards you. Try not to disturb the other two prongs. Wilson mags has lifetime warranty.
Gulf coast guns has them for $15. I will note on mine I have to have the slide open for it to seat but I also have the custom magwell so I'm not sure if that has anything to do with it.Bring your old recoil spring with you just in case it has cycling issues. Just in case.
What price does gulf coast guns have on their 1911 mags?
your mags will lock in on a closed slide, you just need to push a little harder / faster to overcome the loaded ammo spring pressure and mag release.
Thanks for the info. $15 was that new in the wrapper / baggy magazine?
CMP sold 1911 surplus mags new in the wrap a few years ago, limit 10 each member, 4 out of my 10 do Not lock the slide back on the last round, but all feed reliably, all mine were dated 1992 mfg date.