All saboted, jacketed bullets can be hard to load-- the Barnes X-bullets painfully so as well.

The problem is that there are no standards in muzzleloading land as far as bore diameters-- a " .50 caliber" can be .497 - .503" depending on manufacturers.

Pure lead sabots, such as the excellent Dead Centers by www.prbullet.com are easier to load, as are Buffalo SSB' s.

PS
To trac209: a sabot is a " wad."