.45 caliber ammunition comprises bullets (approximately 0.45 inch in diameter), first standardized by Colt's Patent Firearms Manufacturing Company in 1872.
That original .45 Colt round was developed along with the Colt Single Action Army revolver for the U.S. Army in 1871-1872.
The .45-70 cartridge followed the next year, developed at the Army's Springfield Armory for the breech-loading Springfield Model 1873 rifle. Originally designed for use by the U.S. Government, it remains a very popular hunting round 135 years later.
The .45 ACP is a cartridge designed by John Browning in 1904, for use in the prototype Colt semi-automatic .45 pistol he also designed. This ammunition also served the M1911 pistol adopted by the Army in 1911.
The .45 ACP round is almost ideal when used with a suppressor because of its very low operation of 21,000 copper units of pressure.
The .45 GAP is a variant of the regular .45 cartridge, designed on behalf of Glock for more compact handguns. Created by Gaston Glock in 2003, the .45 GAP is a .45 ACP case shortened to 9mm/.40 S&W length with an ordinary .45 ACP bullet over a charge of powder.
The .454 Casull is an adaptation of the .45 Colt developed in 1959. It's bullet and case dimension largely match the .45 Colt with the exception of its length. This is to accommodate a larger powder charge, essentially making it a magnum version of the .45 Colt.
Although not in name, the .460 S&W Magnum is a .45 caliber round, also a magnum version of its parent cartridge, the .454 Casull. It uses the same bullet dimensions as the .454 Casull and the .45 Colt, but it's case dimensions differ from the .454 Casull in more than just length.
A positive consequence of the relationship between the .460 S&W Magnum, .454 Casull, and the .45 Colt is that bolt and lever action rifles and revolvers chambered for the larger caliber can frequently chamber the smaller caliber. The reverse, however, is not true and may result in firearm damage or bodily harm if attempted.
The 45 Raptor is a rifle round developed for the AR-10 and similar firearms. It is a hybrid of the .460 S&W Magnum and the .308 Winchester. It uses the same bullet, powder charge, and primer as the .460 S&W Mag. but is a rimless design matching the specifications of the .308 Win. This allows the 45 Raptor to be chambered in an AR-10 style rifle by only changing the barrel, barrel extension, and using a modified magazine which will retain its original capacity. The receivers, bolt carrier group, buffers, and other components remain the same.