1885:
It is unlikely that Astbury made the barrels, he was principly an action forger and filer, he may have 'fitted' the barrels, and probably just used them as a convenient spot to leave his mark! My understanding is that Andrews finished-up doubles for other makers too, so I suspect he (or more specifically, his employees and immediate out-workers) made and finished the barrels, and finished the gun.

You will have already learned that it is very difficult, often impossible, to determine who actually made what, and for whom, in the Birmingham (and London!) gun-trade. You are lucky indeed to have the CWA and JA marks on your double, this tells better than half the story, and leaves only a little mystery and intrigue!

BTW: IMHO C.W.Andrews was a quality maker who really knew how to put together a gun. While this board will no-doubt assign his name to a low 'tier', his workmanship was second-to-none, and I suspect a good many 'first tier' guns bore the CWA mark before being struck-off in a London workshop!!