Hey, Gunner!
You prompted me on this idea with your recent build. I built up a .300 blk AR with a 16" barrel and an adjustable gas block, with the idea that I could shut the gas off and use the side charging upper like a straight pull bolt action. Finally got it all together today, hopefully I'll get to test it out soon!
It's built on a group buy lower from a local gun board, logo on the side...