Do you get Home Shop Machinist magazine?

If not, you should track down an issue or two and have a good look at it.

There was a design serialized in that magazine, showing the making of a falling block, striker fired action, which they collected together and published as a stand alone book. 

Village Press Publications is the publisher. Worth a look.

The square hole of the mortise is daunting to look at, but if it's a hobby anyway, you are in not a huge hurry. It can be dealt with by shaping, or by sawing and filing, but EDM (the money solution!) is by far the fastest and least risky method.
You soon learn, in metalwork, that you need a tool, to make a tool, so you can make a tool....etc.

If you can find a source of acrylic scraps (aka PLexiglass), they work very well for doing freeform cut and try machining. They also offer the ability to see what is going on inside while the cut is going on, allowing you to play around a bit while laying out inside machining set-ups, and seeing how things will work out.

If you keep to low pressure cartridges, the sky is pretty much the limit to designs. 
If you can get hold of the DeHaas "Single Shot Rifle" series of books, there are a lot of means to an end.

One other method I have seen used, was to machine the action in two halves, and weld the halves together. 
If you can weld, that may be something to look at. 

Take a look at homegunsmith.com. Register and search for "falling block rifle". There are a couple different builds documented there.

Cheers
  Trev

Thanks for the reply's and information.  I am now a smarter, if no wiser man now.  I'll check them out.  Didn't know about the Home shop magazine.

I got an e-mail from the gentleman making the Farquarson [sp] action that he would send me the info on his latest strong build it yourself action that will require little fitting- apparently it has a outside hammer [I assume much like the Sharps or Alex Henry.

Whitey, I believe it is.  The gentleman's name is Gordon and his address is smoke@actioncastings.us  -his e-mail indicated just preliminary info. being available, but that the action could be put together as rifle or pistol, and for right or left handers and required little finishing and no springs to be made.

Probably your best single resorce would be the "Single Shot" series of books by Frank DeHaas.

He laid out all the parts or drew a fairly accurate scaled drawing, for each of the dozens and dozen of rifles and actions he reviewed, ranging from very early to recent developments (up to "his" time, in any case), gave a written assesment of the strengths and weaknesses of each design, and some of the design history if known.

These drawings are very good reference material, and I suspect that a good many firearms have been made from them. General arrangement, shapes and relationships while in positon.  One need not worry much about exact measurements, when one has all the parts that will ever have to work together, on the bench, unlike a production setting where tolerances and mis-measurements could ruin the parts run.

If you have not seen these books, I am pretty certain that you will enjoy them. They are a good bunch of info. 

If you have not seen the Machinist's Bedside Reader series of books by Guy Lautard, I recommend them as well.

Cheers
  Trev

I can't wait to see it Harry!    Bob

Single-Tooling it,as my father traught me to do it, isn't all that hard.You just keep cutting till it fits,if you are building a rifle from stratch, use a 60 degree "v"thread.For god's sake don't use a SQUARE THREAD, unfornunately most original singleshots except the Ballard and High-Wall do use a square thread.THe Machinery's handbook does not even list that thread type,but i've rebarreled two rolling-blocks and am about to do a Sharps side=hammer that has this type. I don't know about the m1rifle, but the 1903 springfield and krag also used a square thread.