Depends on your definition of better. All 3 are capable of taking any game found in North America. The 8mm Mauser carries a little more energy than the .308. The .308 may have an edge in accuracy. The .270 is basically the 30-06 necked down to .27 caliber, shoots flatter, due to higher velocity. This is one of those Ford/ Chevy/ Dodge discussions.
Yes
The .270 is a necked down 30-06. .270 WSM is a necked down .300 WSM. The 270 WSM is faster than the .270, and has a shorter case.
The parent case of the .270 is the .30-06, necked down. The parent case of the .243 is the .308 Winchester, necked down. Aside from the larger diameter of the .270, the .270 has a longer case.
The .243. It's basically a necked down .308 Winchester.
The "parent" cartridge was the .250 Savage, necked down to .22 caliber.
Send me photos of the rifle and of the markings, and I should be able to narrow it down for you. The email address is in my bio page.
no- very much a center fire cartridge. It is the .308 cartridge necked down to a smaller (.243) bullet.
The .357 Sig is a 9mm projectile, loaded into a necked down .40 S&W casing.
I believe the smallest bullet in terms of diameter is the .17 HMR. It is a .22 casing that is necked down to accept a .17 caliber bullet.
There are several rifles, both military and commercial, which have been made for this cartridge. Try to narrow down your criteria to something reasonable.
The .17 Hornady Magnum Rimfire (HMR) IS the name of the cartridge. It is a bottle necked rimfire cartridge- similiar to a a .22 Magnum necked down to .17 caliber bullet. Bullets used in this cartridge may be several different types, but are typically 20 grains or 17 grains in weight.