Sounds like the first step in a good plan. Now continue with load developement by increasing by ½ grain increments up to what you said is max at 22.0 grains.
If, along the way the group tightens up to what you want, then you're home! If not then it's time to try another powder,(assuming you want to stick with the same bullet). H-110 or WW 296 is a standard for the .44 mag. It should be loaded with a mag. primer and the same heavy crimp you're already using. My favorite is Alliant blu-dot. It won't reach the top velocity of the other two, but it's cleaner and uses less to achive it's top velocity.
Another that is said to be good is Hodgdons lil-gun. It was developed for the little .22 shells like the hornet, but it seems to be doing some good work for the .44. I've not tried it yet, mu Ruger SBH has to go back to get a new barrel put on.
The more people I meet, the more I love my dog
They're going to get their butts kicked over there this election. How come people can't spell and use words correctly?