Originally Posted by Muley Gil

1917, 1950 .45 ACP and 1955 Target revolvers aren't "cut" per se. They are all forged for the extra headspace necessary for using .45 ACP cartridges and half moon clips. The half moon clips hold three rounds and the rounds are clipped into the inner radius. Post WW I, Remington created the .45 Auto Rim cartridge which had an extra thick rim to compensate for the extra headspace. .45 AR appealed to those folks what didn't want to clip and unclip .45 ACP rounds into the half moon clips.

Around the 1970s, the full moon clip was introduced that held six rounds, creating a "speedloader" that didn't have knobs to turn or buttons to push.