Rebel Dave: As stated by others, yep-you can load 44 Rus, Colt, and Specials in dies slated for 44 Spec. Dies slated for 44 Mag/Spec I'm not sure. You may be able to turn the expander and seater stems down far enough for expanding and seating the two shorter case calibers. A call to die manufacturers would tell you. My RCBS carbide Cowboy Die set is labeled 44Russ and Special. I load both 44 Colt and Spec with no problem, but bought a separate bullet seating die when I purchased a 44 Mag Ruger.
As far as shell holders, my Starline brass for 44 Spec measures 0.508 at the rim and the 44 Colt, 0.482--only 0.026 difference, but enough to give the 44 Colt some sloppiness using 44 Spec shell holder, a RCBS #18. For 44 Colt I use a Lee #9 which fits real nice and found that a RCBS #3 will also work. Some time ago I read that shell holders for 41 Mag revolver works for 44 Colt. Nope, it's to tight, won't allow ya to stick the rim in. If you use a Lee Auto hand primer, the Lee #9 shell holder works for 44 Colt---the Lee #11 is what I use for 44 Specials. I don't load 44 Russian so I've never looked to see what they take, but I believe they take the same as 44 Spec/Magnum.
I've been shooting and reloading 44 Colt and Specials in a Uberti Open Top and Richards II for around nine years now. Started out shooting smokeless only in the 44 Spec's and black powder only in the 44 Colt's. Did this because I like shooting both types of powders and for cartridge identification. Kept the smokeless on the mild side so as not to 'hammer' the pistols to death. Used mostly Trailboss, Red Dot, and Titegroup. Kept muzzle velocity under 1000fps, mostly in the 850 or so range. Used mostly Lee 200 grain cast bullets of wheel weight hardness, sometimes soft lead. Bought a DD Mav Dutchman 200 grain mold using soft lead for the balck powder loads. Started out using around 25.0 grains of FFF, but switched to using FF (Goex) after reading some posts on this forum by others who reported better results with the FF (Fox Creek Kid was one). Happy with the FF, it is supposed to be a little easier on the gun. Over the last five years or so, all I shoot in both guns is 44 Colts any more. I did load up some 44 Specials with black a while back, but haven't got around to shooting them. I shoot most of my Specials anymore in a Ruger Super Blkhawk.
In both of my Colts, the 44 Colt rims fit fine in the Colt cylinders. Uberti made the cylinders to accommodate using 44 Colt cartridges. As previously posted, you can take 44 Specials and shorten them to 44 Colt length, but as previously written, the case mouth wouold be thicker, may cause problems when you roll crimp the rounds(??). Starline sells 44 Colt, but I have seen it for sale on some of the on-line outfits if you don't want to order Starlines 500 case minimum. Good Shooting. Love shooting the 44 Colts in the older style Colts. Crow Choker