The .360 2-1/4" can be great fun with either black or light smokeless loads. The original British loadings were of the 'miniature express' type with pretty light plain lead bullets - 150 to 190 grs typically - giving 1700 fps or so. If the bore and groove of this one run on the small side as they often do there are lots of .358" cast and swaged bullets to choose from (and you can load it with .38 Special or .35 Rem dies!). If it's larger you can paper patch any of those up to the right diameter. There are even a couple of sources for .364-.366" cast out there as necessary. I'd start with either Buffalo Arms formed brass or cut down some of the currently available Norma 9,3x72R stuff, though you will need real dies to do the latter. There was an article is DGJ a couple of years back by Ross Seyfried about using the .360 2-1/4" that might be a good hook...

Raimey, you should be able to get springs made by a good double gun smith. I had a set made up by Abe Chaber at Custom Craft (contact info -> here <- ) a while ago that have worked well.

John, those rocklocks are addictive! We appear to be on the same slippery slope. Simplicity is good.