Looking at C. Sharps' web site, they do make and sell complete 1885s, and they do sell some types of actions; but, near as I can tell, they don't sell 1885 actions.
Theoretically, you can get a barreled action (only ... no bare action without barrel) from Browning; they show up on their parts list for the 1885. Whether or not they have the caliber you want remains to be seen; but you might try giving them a call.