How do you get the gold desert eagle on mw?

You need to prestige. If you don't know what that means then it means you have to reach level 55. Every time you reach level 55 you prestige. There are 15 prestiges. I'm 6th Prestige :D. Hope I helped.

Also check out my channel on YouTube at YouTube.com/21funfun

And follow me on twitter and Tumblr @FunFunARMY