They hold up just fine, I have loaded them for my 44 Mag Marlin as well. Best accuracy for me was with 9 grains of Unique. They are not the most accurate bullet in my 1894 Marlin being a .429" projectile. .430 & .431 work better in the Marlin lever guns in my limited experience. I have had GREAT success using the 240gr DRG semi wad cutters with the lube groove. My Marlin doesn't like the Hornady moly coated 240gr projectiles either.