Rebated rim

Rebated rim

Rebated rim cartridges have a rim that is significantly smaller in diameter than the base of the case, serving only for extraction. Functionally the same as a rimless case, the rebated rim provides some additional benefits when considered in conjunction with other cartridges. One example of a rebated rim cartridge is the .50 Action Express (or .50 AE), commonly chambered in the Desert Eagle pistol. In order to simplify production, and to decrease the cost of ownership, the .50 AE was designed with a rebated rim which matched the diameter of the rim of the .44 Magnum, which was the most common caliber used in the Desert Eagle. By using the same rim dimensions as the .44 Magnum, a Desert Eagle could be converted from .44 Magnum to .50 AE by merely changing the barrel and magazine. Other convertible cartridges, such as the .41 Action Express used in the short-lived Jericho 941 convertible pistol, would function in the same magazine, and thus required only a barrel change to change caliber. The recent (early 2000s) Winchester Short Magnum, Winchester Super Short Magnum, and Remington Ultra Magnum and Short Action Ultra Magnum families of rifle cartridges also feature rebated rims. In these cases, the rim was designed to fit bolt faces for existing magnum rifles, but the case was made wider to allow a greater powder capacity.

The .50 Beowulf also uses a rebated rim design. This round is used in specialized AR-15 upper receivers, and the rim matches the size of the rim of the 7.62x39mm, allowing those parts to be used in the custom-built upper receivers.

Rebated rims were also a feature of the cartridges of automatic cannon derived from the 20-mm Becker, of which the best known belong to the Oerlikon family. These blowback-operated weapons feature straight-sided chambers that are longer than necessary to contain the case. The face of the bolt has the same diameter as the case and follows it into the chamber. This means that the extraction claw also has to fit within the chamber, and therefore the case has a rebated rim.

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5 years 48 weeks ago, 11:50 AM


zx12rmike's picture

President Pro Temp
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You have been posting some good stuff, Thanks Snaks

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5 years 48 weeks ago

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