You're going to have to do a bit of troubleshooting.
From what you're saying, the pistol will not close fully on a loaded round. If this is correct, check the following:
Are you shooting factory ammunition, or reloads that have proven reliable in the past? If so, go to the next step.
1. First, slowly cycle an EMPTY gun (move the slide back and forth). Does it go into battery easily?
If it does not, and needs pressure to close, you might have a problem with the barrel hood or the fit of the barrel link and slide stop pin; or even the fit of the barrel lugs and the slide.
If it does close easily, proceed with the next check.
2. Can you cycle the slide VERY easily without too much effort? If so, your recoil spring might be weak. Another indicator is if (when fired) brass is ejecting into the next zip code.
If this is the case, install a Wolff recoil spring. Factory weight is 16 lb; I usually run an 18.5 lb spring.
If it passes the spring test, check the bottom of the extractor as described above. You'll be looking at the part that actually engages the rim of the cartridge. The bottom should be gently beveled. If it is not, you can do the job with a swiss-pattern file and a few careful strokes. Just barely break the bottom edge; clean and reassemble; then fire a magazine to prove the pistol.
Hiding in plain sight...