Consider this to be a public service announcement.
Always, always, always remove your moderator from your rifle when it is not in use. This is an Accuracy International barrel that was returned to the cabinet with a reflex sound moderator still fitted.
Also, please remember it is not only carbon steel barrels this applies to, stainless steel barrels can and do corrode as well.
While I am here, a quick update on the XM177E2 project, some more parts have arrived and hopefully I will be able to assemble and test fairly soon. Next job is to machine the correct receiver extension nut, the early versions were designed to be tightened with a pin spanner and the later are castellated. There are so many small details to get right if this to be vaguely true to original. Right now my number one mission is to find an aluminium butt stock which looks nigh on identical to the one in this picture but is not plastic.