Because why set up for an action you can get from the trade also after 1881 greener had a propriety gun they were selling greener wouldn't have to increase it's capacity and could use outworkers to finish A&Dactions or barreled actions.
I’d say because they had an even bigger investment in their own rather large factory, craftsmen, apprentices, machinery, tooling etc. Factories that large didn’t normally use the out worker system that the small makers did. They didn’t have to, they accomplished damn near everything in house. The only exception being a requested particular engraver by a client for a custom ordered gun. I doubt W&C Scott, Webleys, BSA, etc ever used the outworker system either.
Maybe very early on in the A&D era, Greeners used actions from the trade, solely because they had to because of patent laws and a learning curve (a relatively fast learning curve I’d imagine with their expertise being pretty damn competent in gunmaking already) in making an A&D action.
As large as Greeners was, with their expertise, manufacturing capacity and factory space, I don’t think it would be too much trouble to set up a couple machines to machine up a&d actions (not difficult) and parts (not many).
Greeners made A&D actions for a long time. Lots and Lots of A&D empires around the world in the old colonies.
Obviously we aren’t talking about the very late A&D guns that were made by Webley & Scott for Greeners in the 50’s and on. Those obviously aren’t “really” Greener guns.