Go here
http://www.wiitech.com.hk/eshop/index.php?cPath=69
You can find amazing upgraded parts for the A&K and Magpul Masada. All machined Aluminum. Just make sure you use the $ conversion tool on the top right of the window.
You will have to create an account to use the site, but this only takes a day or two to set everything up.
Good luck!