Very nice what a good looking rifle, I like them. Not sexy but very functional and robust.
I had the opportunity to examine one of them, 14 or 15 years ago, for a week and took some measurements. Back then I had built a Freund, Farrow, and Fraser so a Fields would be the next logical choice. I haven't built one yet but I did find the dimensions I took the other day. My last name starts with F and the guy who lent the gun to me (deceased now) his name started with F.

I too am fond of the English single shots. One good thing is I have a couple more in the same caliber, including a Westly Richards Deeley and Edge auctioned rifle. Just have find more brass, so each can have their own.

That's a nice Field. Would jump on one if I could afford it. Here's my 500/450 No 2 Musket. A Westley Richards takeoff on an internal hammer Peabody. Bought it for $10 in 1964. The good ol' days.

You can make the brass from 470NE which isn't too hard to come by these days - unless you need proper headstamps then Bertram is about the only maker I know of.
Does your rifle have a patent use number on the underside?

Fazer, just from the looks of things, if that's your rack in the background, you should add a Martini variant or two...   Nice, very nice!!

I don't want to hijack the thread however, among so many single shot aficionado's seems a good place to ask.  A friend told me someone is making a Farquharson kit.  Does anyone know if that is true?

I imagine that the problems with using smokeless stem from the firing pin being so large.
I don't recall seeing an original smokeless Field falling block except for some H&Hs and I suspect that they probably bushed the firing pins on those rifles.
A modern NfB load should be just fine in that rifle and the 500/450No.2 Musket is easy to load as I am sure you know.
The action is so simple and easy to dismantle, inspection of the block etc. is very easy.
Mine is a 500No.2 and a wonderful rifle to shoot although it is a little tired in the condition department.
Also, the number on the action is a use number of the patent which covered both the Field tilting block and falling block designs.  Not many of these around and generally most owners find them so simple and functional that they rarely leave their collections.  Sort of the English High Wall, only better

I could be completely wrong, but I seem to recall being told that someone, I think in Calf, was making Field's actions for shotguns. Can't tell you if it is true or not. Maybe someone here can shed some light on this. They weren't called Fields of course.