I reached rank 20 recon but can't unlock the kar98k

Hi @lopfter This is a fairly common issue that hasn't been resolved. The gun should unlock and appear for you to claim in the Armory eventually, but you may need to play more matches or rank up again first of all.

If all else fails, EA Help should be able to assist you if you reach out to them.

EA Help Contact:

https://help.ea.com/en/contact-us/
https://twitter.com/EAHelp/
http://www.facebook.com/EAHelpHub/