What action to use?

[Bugscuffle]

I am looking for a Sharps or Highwall or similar falling block action that I can barrel with about a 30" 45-90 Express barrel. It could also be a 45-70 action/barrel. They are easily reamed out to 45-90. The rub is that the action/barrel will have to handle the 45-90 Express cartridges with chamber pressures of 45,000+ psi.  I want to end up with a real special gun. It should be a pistol grip stock with cut checkering and some pretty fancy wood. I really like forend caps, and a nice pistol grip cap should really set it off. Another upside is that it will still shoot the 45-90 BP cartridge. The exact sights I'll settle on later, but it will be a tang sight (Soule?) and a Globe front for now I need the action that will stand up to those pressures. My first though was to a Ruger #1 or #3 action. There are a ton of stock makers out there that have stocks for the Ruger on hand or can make up a decent stock for me and the barrel is an easy fix. My only questions about the Ruger are, is there a set trigger available for this action, and howcan I mount a tang sight on the Ruger tang? Oh yes, can I still shoot the 45-70 cartridge in the 45-90 chamber? The only realdifference is that the 45-90 is a littlebit longer and they are both straight cases. Are there any other things that I should be considering? I have no constraints on rules or weights etc. This will not be used in competition. I may take it hog hunting, but mainly I want to go to the range and play Quigley or maybe Jungle Jim the elephant hunter.

[Guns Garrett]

If you are set on a falling-block type action, Sharps or High wall are about the best to go there.  Unless you can find a "parts gun" with those actions, prepare to pay well for a new-manufactured one.  For about the same price of one of those, you could get a Ballard, Stevens or Hoch action from Meacham Tool & Hardware or Ed Yost.

Remington Rolling Blocks are not as high-priced as those you mention, but the hammer may need mods to accept longer shells - though I think 45-90 is not a problem.   Very strong action, simple, with few moving parts.  Still plenty of those old #1 military actions around.  Set triggers are available, but pricey.

Treebone Carving offer several styles of stocks for the RB, including pistolgrip, with or without cheekrest - also Highwall, Sharps, Ballard and Stevens.  Forearms can be had with ebony, steel, or pewter tips.

If you are not restricted to "visible hammer" requirements (since you were considering a Ruger), Martini-Henry "parts guns" (and possibly actions only) may be available from International Military Antiques (IMA-USA.com).   Their "untouched" guns are very inexpensive, and most reports by buyers tell of actually being in excellent, shooting, condition after careful cleaning.  Martinis are very strong actions and made the transition to the smokeless era without modifications.  I don't think set triggers are readily available, but they have been made - probably custom. Greener-Martini "police shotguns" are also VERY strong and a favorite of BP bench shooters.

[Blair]

Bugs,

The cost of setting up or building " a real special gun" can be quite high.

If you don't mind me make a suggest to you... set it up to where it will server you well in the greatest majority of shooting/competition sports. Usage and cost should determine what action would be best for you to use. Early outside or exposed hammer type actions will offer you greater overall usage. (Just my opinion)
You want a .45-90, then set it up and only shoot .45-90. Don't cheap out thinking .45 70 will serve you as well... it will not!
Just some thoughts on my part,
 Blair