Raven Concealment Systems just introduced the TopStop, a cover that closes off the open parts of a detached upper receiver group and retains the bolt carrier group and charging handle.
I can think of several times that I wish I had something like this. For instance, when headed to the range with multiple AR-15s to zero, it can be handy to just carry one lower receiver and multiple uppers. A cover like this would protect all the components of the upper when they are all stacked in a bin together. It would also be great for those of you who carry AR-15s in discreet take-down cases, especially if that case isn’t necessarily meant to carry an AR-15.
Check out the handy TopStop at Raven Concealment Systems.