I tend to be attracted to the road less traveled and Martini Henrys kind of fit the bill in the US. I have 2 Mk IIs and have wanted to get them going but brass has been so expensive. So I ordered some made up by Xring Services aka Martyn Robinson. They arrived today and he did a superb job. He offers a number of items for other obscure firearms and he reasonably priced too. I have fiddled with making this cartridge and he does it really well for that price. He only works off email and there is no website but he is very accommodating and I am sure he'll be glad to help you. Time now to go burn some Goex.
Scott Ingle