Re: 1911 slide will not lock back after last round
To break it down and elaborate a bit.
Suppose you have a 1911 which has a frame which is a few thousandths thicker (Springfield’s) and a slide stop which has a lobe which is a few thousandths short and a magazine where the slide stop engagement notch is a bit worn or out of spec and the result will likely be no hold open on the last shot. Of course, if any one of these elements is out of spec enough it can cause the no hold open problem, but its usually a confluence of more than one of the elements being out of spec.
Chip McCormic uses stainless followers, which eliminates much of the wear issues polymer followers have and he keeps his tolerances tight and uses one of the best springs of any mag out there. Other good mags as mentioned by others here, and I concur, are the Trip, Wilson ETC (though they still have a polymer follower) and Ed Browns. Often, just a good mag fixes the problem.
As stated earlier by another poster, Hilton Yam’s 10-8 Performance Gen 2 Slide Stop is one of the best and his tolerances and quality control are excellent, so you are not likely to get an out of spec slide stop and this often this fixes the problem. (where you are having the problem using good mags)
If you still have issues, one of the solutions is to get a slide stop for a 9mm/.40 1911, which typically have a lobe of .220. You can then re-contour it to the proper length of .200" as measured from the back of the interior of the slide stop lever on your specific frame.
And, of course, use good mags.