When I first tried a .44 mag, I ordered the Lyman 429244 GC mold; later I got the 429421 plain base mold. At that time, my standard load was 21 gr 2400 for about 1279 fps. I never had any serious leading problem as long as I lubed the bullet well (alox and later Lee Liquid AAlox); the bore remained clean. I don't think you'll gain much with gas checks.