Same reason "they" make about 30 versions of a 30 caliber and probably 10-15 of a 224 caliber.As far as a "7mm", the most popular one and the one most guys are referring to when they say "7mm" is the 7mm Remington Magnum.I always refer to it by it's full name so everyone will know which cartridge I am referring to.The .284" bullet is carried by a whole slew of cartridges.Starting at the lower end of the power scale we have the old 7x33 Sako,7mm International,7mm IHMSA,7mm BR Remington,7mm-08,7x57 Mauser,284 Winchester,7x64 Brenneke,280 Remington,7x61 Sharpe & Hart,7mm Remington Magnum,7mm Weatherby Magnum,7mm Dakota,7.21 Lazzaroni,7mm STW,7mm Remington Ultra Mag,7mm Remington Short Ultra Mag,7mm Winchester Short Magnum and probably a few I can't remember right now excluding Wildcats(another story). These are all different cartridges that use a .284 inch bullet, so all are "7mm's" Many people new to the shooting and reloading hobbies confuse the "caliber" or "bullet diameter" with the cartridge name. They are two different things.When referring to a "7mm" you must use the name of the cartridge,ie: 7mm Remington Mag or 7x57 Mauser etc.As for which one is the "best",well that depends on what you want to do with the rifle and what your requirments are for the cartridge."best is relative and has different meanings for different people.The 7mm Shooting Times Westerner(STW) may be "best" for dropping whitetails at 400 yards but it wouldn't be "best" for a target rifle, something like the 7mm-08 might be "best" for this in someone's mind.When people tell me thay use a "7mm" always ask "which one" and most can't tell me.A co-worker of a friend stuffed a 7mm Express(280 Remington) into his 7mm Rem Mag this season and proceeded to blow the floorplate out of his rifle with a ruptured case. He was lucky. YOU HAVE TO KNOW WHICH 7MM YOU ARE DEALING WITH!

Edited by - riflenut on 01/02/2002 00:33:09