A lot of old wives tales still persist about
"the 240-gr handgun bullet in a .444",
"the .444 cannot stabilize heavy bullets"
and "the Marlin Micro-groove cannot shoot cast bullets".

Go read the 3 articles on Beartooth Bullets website.
Borrow a .444, load it with some 240-gr Remingtons, Hornady 265-gr , and Hornady 300-gr factory loads, and shoot it for groups and into something substantial, like 36 inches of wet potter's clay.