New doesn't necessarily mean good. If some mags work, and others don't, then there is most likely a problem with that mag. If they were cheapies, I might put them up for the end of civilzation. You might try a new spring or one of the magpul followers. I bought a couple of the pmags from muddawg95yj on this forum. PM him for a good price if you decide to go that route.
Off topic, but I noticed you have a couple of .45's. What do you do with your brass?