Caliber conversion device

Additional variations may allow centerfire weapons to fire rimfire ammunition and/or retain autoloading function with the smaller cartridge.

Rimfire cartridges, with their low cost, noise, and recoil, are ideal for use in a supplemental chamber, except for the fact that the firearm in question is almost certainly a centerfire design.

This means that supplemental chambers that use a rimfire cartridge must also provide a special offset firing pin.

When this insert is hit by the firearm's firing pin, it is pushed forwards, which causes it to crush the rim of the rimfire cartridge, igniting it.

[4] Since the supplemental chambers are approximately the size of a normal loaded cartridge, they will usually feed from a magazine, though they will not provide sufficient energy to cycle an automatic action.

[citation needed] Sleeves that exceed the chamber length are generally used in break open actions, which allow easy insertion and removal.

Like supplemental chambers, caliber conversion sleeves completely surround the new cartridge case, but cannot be ejected or fed from a magazine, so they only offer a single shot per barrel without manual extraction and reloading.

[7] Many makers offer longer inserts, though due to the variations in shotgun bore diameters, these usually require custom manufacture.

[citation needed] Conversions for automatic firearms are often more complex than those for single shot or manual repeaters, as the difference in power available to the operating mechanism can be significant.

This typically involves replacing the firearm's bolt or slide with a lightweight part lacking the locking mechanism, and a reduced power spring.

[9][10] One exception to the use of a special lightweight bolt was the Colt Service Ace, offered as a complete pistol or as a conversion kit for the M1911.

The 1903 Mark I differed from the standard rifle in that it had a slot cut in one side of the receiver, which served as an ejection port for the Pedersen device.

Potential utility for short range target practice or killing small pests is limited by significantly reduced accuracy of handgun bullets encountering faster rifling twist after gaining velocity in the long jump through the unrifled adapter.

[14] Some European conversions exist for special gallery cartridges, similar in concept to the .22 CB rounds, which use a primer but no gunpowder.