I'm with Dave, and Kermit, on this one. I wrap my hand around the horn, with my thumb, and forefinger, extending beyond the neck of the horn forming a sparkless, adjustable, funnel, that doesn't get lost, or broken. And in my experience, it spills less powder than using a funnel.
Muzzleloader shooters should definitely adhere to the KISS rule, or you will end up with more gadgets than your truck can haul.
Hungry Horse