Some folks experience rounds skipping the follower on Atlas magazines with the competition followers.
I believe that this is due to undersized brass or perhaps even an issue with the overall length of the round. I personally had this issue when I was using the Dillon and Lee undersized 9mm sizing dies. It was happening on all 6 Atlas magazines I had at the time.
The resolution was to either use the Grams or Taran Tactical followers. I was also using the Grams springs for a while, but I did notice the spring contacting both sides of the magazine where it starts to neck down. I didn’t experience any feeding issues with the springs, but it didn’t inspire a lot of confidence. Also, the Grams followers are quite a bit thicker. While I didn’t lose any capacity, it was still a bit stiffer loading them.
So I landed on using the Atlas 11 coil springs with the Taran Tactical followers.
This did require some light modification though. The Atlas springs bend at a different angle where they loop into the follower. I used a small pointed Dremel bit to lengthen the hole on the follower towards the front to allow the spring to catch.
Once this was completed, my issue with rounds skipping the follower disappeared. I also currently have 2 Atlas magazines left in their stock configuration that I haven’t experienced the issue with since switching to the standard Lee sizing die, but I also don’t have enough miles on those to be certain the issue doesn’t still exist as it was pretty intermittent.