The Mk 17 has a bug where the mag size is incorrect most of the time for example
you equip the 30 round mag and the 20 round mag appeares it's not just me that has this it's everyone because I have even seen it in YouTube vids and on my friends
it's annoying and if you are a dev reading this or someone who can report to a dev please come in contact with me so I can report a few more