The most accurate .44mag Rifle I ever owned was a old Remington model 788. If I remember correctly it had a 22" bbl. That was a GREAT shooting rifle, and it was a long time ago, but I think I was consistently able to shoot +/-2" groups at 100 yards.
I had one of those I.M.I. pump-action Timberwolf rifles and it was very accurate too. The rifle itself weighed a ton, probably because it had a long, fat (almost a bull or heavy) bbl. And 10 rounds of .44 mag as fast as you could pump it was comforting in the Rodney King Riot days.
I've owned 2 of the older (tube mag) Ruger .44 carbines, and while they were good at 50 yards I just could not consistently get decent 100 yard groups out of them. Probably more me than them, and maybe I was spoiled by the accuracy of that old 788, but I just didn't feel secure taking 100 yard shots with them.