Find out what the terms are to "guarantee" your container load or whatever getting near the top of the list to be filled. The market seems to operate on a commodity basis to highest bidder at times.
Let's say you found a way to get Caledonian Shells to manufacture enough ammunition to sell you some, then you need the advice above to "fix" the costs at agreement time and to make certain that when the shipment arrives, you'll be able to take possession.
There seem to be ever changing licensure rules too.
I don't know if it would be helpful to speak with others but there must be a reason so many have gotten out of the business, many have never gotten in, and our shell supply is so limited.
For example, I'd speak with the folks out at Westley Richards in Montana as they have had some fun getting their own-name shells in from time to time.
The owner of Woodcock Hill had spoken about trying to get some British shells as an alternative to RSTs during the hiatus of that product from our supply line.
Charlie at British Sporting Arms in Millbrook has spoken of inquiries from clubs trying to bring over shells. Don't know of anyone actually pulling this off but that may be more like what you want?
Perhaps what Morris Baker had to do to bring in components might be helpful since he is also in Pennsylvania with RST?