There are probably three reasons why you are thinking of taking up hand loading your ammo. Economy, better accuracy, or a certain purpose for which factory ammo is not well suited.
Take the present popular .243 Winchester cartridge. Factory ammo now costs $20.50 a hundred rounds. You can reload the fired cases with an 85-grain bullet, 39 grains of 4895 powder and the primer for about $5.30 not including your labor and the initial price of the tools. Some difference! If you are blossoming out with a brand new rifle, particularly if you are not already a very experienced rifleman, its going to take you about 500 rounds of careful range shooting to develop good marksmanship. You should become so familiar with that rifle that both you and it will perform at the maximum, either on the target range or in the hunting field.
Take the .243 rifle above cited, well bedded and with a good scope. I must have fired more than 200 groups at 100 yards from bench rest with two such rifles, and I have seen many other shooters firing this caliber. Factory ammo has averaged groups of about 1.75 inches; the above handload in about .90 inches.
Perhaps you have a .30-06 rifle, and you want to hunt turkeys with it. All factory cartridges will blow turkeys or grouse, or rabbits into sausage meat; but you can develop a handload which will kill them neatly without spoiling any meat.
But perhaps you think that you want flatter trajectory, greater velocity, or more killing power than you can get with an equal weight of bullet in factory ammo. This is a “will-o’-the-wisp.” You can’t do it and still have accuracy, safety, and dependability.
A few years ago the editor of one