The 1894's have Ballard rifling, not Microgroove. While the other calibers have a 1 in 16 twist the 44 was done expressly for a cast bullet (200 to 240 gr)at moderate speeds for Cowboy shooters.
I thought that the 1894 .44s had both ballard and microgroove, with all of the octagon CB rifles being ballard only, but round barrels either, in different years. Am I reading wrong?
Twist rates are simple math, the Greenhill equation. Longer bullets generally require faster twist to stabilize and since a given caliber is diameter constrained the only way to add mass is to make the bullet longer.