The 1911 Gap
When considering a used 1911 with a non-ramped barrel, expect there to be a small (about 2mm) gap between the frame's feedramp and the barrel's feedramp when the slide is locked back. This is normal. It's supposed to be there. If it is not there, the pistol will never feed correctly, and the only solution is to weld-up and recut the frame, cut out the frame and install a ramped barrel, or replace the frame. None of these options are fiscally attractive.
Always check for this gap. If it is not present, pass on the gun. You will save yourself a lot of anguish.
Here is what you want to avoid.