Even though they are called .44 caliber, the actual groove diameter of the ROA is about .457, (.454?), and takes round ball of that diameter.
Dragoon & 1860 Colt replicas are still called 44s, but use a .451 ball, as does the Rem 1858 New Model Armies.
The R&D and Kirst conversion cylinders for all of them are mostly in .45 Colt, aka .45 Long Colt. It just so happens that the barrel diameters are perfectly compatible.
The "inflated" price may be because the Ruger management , in their infinite wisdom, have discontinued the Old Army! As the ROA does not replicate any historical firearm, the only reasons to buy them are.
1. They are traktor tough!
2. They are a LOT OF FUN!
Maybe, just maybe, RUGER are dreaming up something newer/older, and better?
Ridge Runner; There WAS a round top version that CAS folks love. In fact, I shot a pair (borrowed) in England, at a SASS match last month. Never a glitch, and every round went exactly where it was pointed! Wherever that was, but it is always the nut-that-holds-the-butt.