Good morning
Marlin rifles for too many years have been sold with fat throats and barrels. Ranch Dog Molds were designed to "fix" the issue.
Those originals have been copied by several mold makers that advertise here. Fat noses to fill the throat and fat diameters to keep the pressure to the rear of the lead slug piston. Large flats on the nose give good energy transfer on target.
Push them hard and fast and they normally will produce.
Especially in the Marlin 44 mag barrels you are faced with that slow twist. The faster you push the slug the more rotation speed is transferred to the bullet giving better stability down range. Happily the 41 mag has a 1-20 twist.
Mike in Peru