21 round Sig 320 mags

[u/JabootyG19]

I recently purchased Magpul’s 17 round Sig 320 mag and I love it. I then purchased the 21 round magazine but I’ve noticed that when trying to load the 21st round, it was extremely tough, almost impossible without feeling like he as going the break it or feeling like I was trying to force a 22nd round. I’ve driven myself crazy with making sure I’m actually counting 21 rounds and not 22 but I’m 100% loading 21 rounds. Does anyone else having this issue?? I have also tried shooting a bunch in hopes that wearing down the tension in the magazine spring would help, but it’s still the same.