Now there isn’t officially a Block III variant of the MK18, but many sources show various groups using the Geissele MK8 rails. The name is part tongue in cheek and part reality. Other rifles are currently being evaluated but Geissele MK8 rails may very well be the future of the MK18. In the following video I discuss what components went into the build and then a well versed AR-15 armorer puts the pieces together.

https://youtu.be/kzUnYypQAv4