This needs to be a sticky or something...... go to the powder manfacturer and look up their load data on-line. Unless you are shooting something the shape of a cigarette with a weird bearing surface, 75 grains in one bullet is going to be the same (or safe enough) going 75 in another bullet. Someone is going to get killed following some wild goose chase anecdotal load info. As to COAL, it is a useless measurement. Develop your loads to shoot most accurately, regardless of how short/long they are...Bullets should be seated in relation to your barrrel's rifling. too long, and the bullet falls out of the case or the bolt won't close. Too short and the bullet falls into the case.