how to get a team deathmatch supremacy coins

Your team must win by reaching the ticket limit and winning by at least double the amount of tickets (so, for example, 400-200). Pretty difficult, but happens.

Thank you soooo much for answering..I looked on YOUTUBE and couldn't find anything...
yes that is truly a challenge lols.

I'm premium and preordered hardline..
my friends have the gun CAR-556
I DONT can you explain why?

As far as I'm aware the release of batlepacks responsible for extra guns was pretty bugged. This thread http://answers.ea.com/t5/Battlefield-Hardline/INFO-Missing-Battlepacks-updated-April-6/td-p/4413620 has a bit of info. As you already got the game a while ago, I suppose it all boils down to contacting EA Support (at least I don't see anything else that might help at this stage).

1 Click on the following link: https://help.ea.com/contact-us
2 Make sure that you're signed in
3 Enter the name of your game and click Next
4 Select the platform you play on and click Next
5 Select the topic and describe the issue
6 Select a contact option. Note that you may have to wait for a while.