The reason he said that is because 4227 is typically a pistol powder, 25 ACP, 357, 38 44 mag etc.....I do see it listed in the Hogdon manual for 356 Winchester, and 30 Carbine, but no other rifle bullets bigger than 22 Hornet, and 222 Remington Mag, but is on the bottom of the food chain for these. What he probably meant was that you should buy a pound of more appropriate powder: Varget, 4895, H-335 etc. I would tend to agree in my limited experience. USE PUBLISHED LOAD DATA, And Only the powders and data that are recommended for your cartridge. After you are more experienced, maybe you can stray from the recipe....If you are not absolutely sure that your ammo is properly loaded, Destroy it. JMHO