Slide Fire debuted its own belt fed AR-15 at Shot Show 2017. It is a modified AR15 with a detachable belt receiver.
The belt fed into the side of the AR with the help of the feed system. The feed system is attached to the side of the modified AR receivers and can be removed or installed without tools.
Once the feed system is removed, the Slide Fire AR can resort to using standard AR-15 magazines. Slide Fire is proud that their belt fed AR can use standard M27 links. The same used in the M249 SAW. The Belt-Fed AR retails for $3500. At the moment they are only sold as complete firearms.