Double rifle

The double rifle, also known as the double-barrelled rifle, is a rifle with two barrels mounted parallel to each other. Synonymous with big game hunting in Africa and India, the double rifle is a purely sporting weapon with no military heritage.

The double rifle is usually hand crafted and is considered by many to be the pinnacle of sporting rifle design, it is not designed for long-range accuracy but instead for the security of an immediate second shot.

As with double-barrelled shotguns, modern double rifles are all made with either sidelock or boxlock actions, although occasionally old hammer rifles can be found. The majority of double rifles have been built on the boxlock actions as it is a simple design with few parts that can fail and consequently it has an outstanding reputation for reliability. The sidelock action, with its lockwork operating behind the main action body, has exceptional inherent strength and as a result could be built on slimmer action sizes in proportion to the calibre, although it is far more labour intensive to manufacture and so more expensive.

Most double rifles manufactured today, especially those designed for dangerous game, are manufactured with selective ejectors which greatly speeds reloading. However many old hunters preferred non-ejector rifles, feeling that with practice they could reload just as quickly, these rifles can still be found and usually attract a slightly lower price.

Double rifles can come in two barrel configurations, over and under designs (usually abbreviated as O/U) where the two barrels are mounted vertically one on top of the other, or side by side (usually abbreviated as SxS) where the two barrels are mounted horizontally next to each other.

For dangerous game hunting, side by side rifles are usually preferred. This is for a number of reasons but predominantly because the barrels of an over and under gun must be pivoted much farther down to clear the lower barrel for reloading.

During manufacture the barrels of double rifles require "regulation" to ensure the bullet paths from both barrels are aimed at a common point of aim. This can be done to ensure either the bullets 1) parallel each other closely at all practical ranges, or 2) converge at a given range, beyond which they begin to diverge. Because of the need to regulate a rifle to a specific loading of its chambered cartridge, once regulated a double rifle cannot satisfactorily shoot bullets of different weights or velocities, as it usually affects the accuracy. The process of regulating a double rifle’s barrels is complex and can be time consuming, significantly adding to the cost of the rifle.

...
Wikipedia