FloppyD, yeah, you'll get a grin on your face with the H110 loads... as ArchAngelCD says, you need to keep the case pretty full with H110; Hodgdon does not recommend that you load anything with H110 (same goes for W296, it's the same powder) more than 3% below max...
As to the primer needed to ignite the H110; I did some testing a while back when the claims that a Magnum primer was necessary (some books use it in their recipes, some don't) to ignite H110. My findings (posted somewhere in this forum) were that everything I tried worked fine. I tried Magtech Large Pistol Primers (these were the most consistent in my gun, with my brass and 240gr XTP bullets--surprising, yes, as the Magtechs were less expensive), CCI Magnum, CCI Standard, and WLP primers. All worked OK, with WLP being the least consistent. I did get like 20fps more with the CCI Magnum primer. I tried putting the gun in a cooler (in a sealed bag, and it's stainless, which I cleaned well after the test), along with some test ammo and a bunch of ice for an hour or two before going to the range the second time... all fired OK, velocities were a little lower (normal, given that the first time I shot in near 100 degree temps), no hangfires. I say test 'em all, see what works good for you. A chronograph is a necessity in figuring out this mystery.
At any rate, H110 is a lot of fun to load up in the .44 Mag. I'm probably going to try AA#9 to see if I can go any hotter, but I think I've hit the wall with the .44 Mag... If I feel the need for more power, I can always get a .460... that thing is a cannon... a dude fired that at the range the other day, and I swear it was louder than an AR or .300 Mag rifle with a muzzle brake!