I'm not sure how to delete the previous post, but after much research, it appears that the X-Products side-charging upper receiver should accommodate the Dolos, so I'm keeping these things. Now I just have to find rails other than Yankee Hill that work with Dolos, as nothing in stock is long enough for my Grendel. The only 15" rail in stock will not accept a bipod. Boo! This is a work in progress.