I have an 044-1/2 in .22-15 SS. C-H 4D made the loading dies I have. I've found the Ideal 63gr PB factory standard, the 228367 60gr GC for the .22 High-Power and the 228151 45gr PB for the .22 WCF all work. I have the 22638 HP but haven't checked it out yet.
The groove diameter is nominally .226". Mine is 0.226-0.227" by my measurements. The bore is not mint, but not pitted; just sort of dark along the edges of the grooves.
I've tried 4759, 4198 and Benchmark, trying for loads that would bulk up in the long case and gradually accelerate the bullet by progressive burning. I don't know how these would work in a 44 action, but I do know that it's possible to pop primers with a 1 gr overcharge of 4198 in this caliber. It only has buckhorn and blade sights, so fine target shooting probably won't be possible. I got the impression that this was a sort of black powder express cartridge for small game and varmints anyway.
Right now the best loads mostly go under 2" at 50 yards. I need to try black powder in this caliber; it's on the "to-do" list.
Any smokeless load development for this caliber is going to be seat of the pants dead reckoning and gun specific. Might start with the lowest recommended loads for cast bullets in the .22 Hornet and gingerly proceed from there.
The Rocky Mountain cases are very good, but being turned rather than drawn, they won't stand full length resizing for very long without splitting at the necks. Don't ask me how I know this.