Thanks for the report, u/AtomowyFigiel! This is caused by an issue with the Magazine Size perk. We're currently looking into it.
This thread was added on April 07, 2020, with posts from EpicBoaty.
Original Post
https://i.redd.it/o5apnzxqcer41.png
That’s funny because I have MUTLIPLE weapons without the Mag Size perk that are still affected.
Would you be able to get me a short video clip that shows the weapon, its perks, and the ammo bug?