Rimfire ignition
The rimfire is a type of ignition for cartridge ammunition .
history
The rimfire cartridge , next to the Lefaucheux cartridge, one of the first standard cartridges with a metal case, was originally a type of ammunition in which the explosive mercury was also the propellant. The inventor was the French gunsmith Louis Nicolas Auguste Flobert, who had been using these Flobert cartridges for Teschings manufactured by him since 1845 and patented them in 1846. The first company to mass-produce weapons for such refined cartridges with an additional powder charge was Smith & Wesson with the Smith & Wesson No 1 revolver in .22 caliber, the Smith & Wesson No. 2 Army and the Model 1 1/2, both in .32 caliber. The first repeating rifle used in greater numbers with rimfire caliber cartridges .44 was that of Benjamin Tyler Henry developed in 1860 and in the American Civil War used Henry rifle , which in the New Haven Arms Company (later Winchester Repeating Arms Company was made) to the 1866th
technology
In contrast to the today usually conventional cartridges with centrally arranged in the sleeve base primer ( " centerfire ammunition ") is squib in rimfire cartridge of the sleeve into the bottom and hence also in the inner circumferential groove of the outside projecting hollow rim of the sleeve is cast. When the firing pin hits the edge of the case base from behind, it is squeezed, which triggers the ignition of the primer in the groove and, as a result, of the propellant powder in contact with it.
The advantage lies in the simple and cheap production by deep drawing the sleeves, since no additional parts and production steps such as primers are necessary. The disadvantage is that the ignition due to the squeezing of the edge results in a low maximum wall thickness, at least in this area of the sleeve. For the above reasons (deep drawing, ignition), soft material is used for the sleeve, initially copper , later brass with a high copper content ( tombac ). The combustion pressure and thus also the maximum projectile energy are limited as a result. Another disadvantage is that once fired cases can not be reloaded because the case edge is irreversibly damaged by the firing pin impression.
In order to avoid misfires (failure of ignition), the Henry rifles , the Winchester rifles Model 1866 and the Swiss cousin rifles were equipped with double ignition, which struck on two sides of the cartridge rim.
Today rimfire ignition has completely disappeared from the military sector, but is still widely used in small-caliber cartridges, for example the .22 lfB cartridge or the .22 WMR (Winchester Magnum Rimfire) , which is mainly used in sport shooting and shooting training where the Disadvantages are negligible.
In addition, this type of ignition is used in bolt-firing tools in the construction sector and slaughter guns, provided they are still operated with propellant cartridges.
Differentiation from rim cartridges
In some types of weapons, such as with revolvers and hunting shot rifles also be marginal cartridges used with center-fire percussion. However, the solid rim of these cartridges has no relation to rimfire ignition. It prevents the cartridge from sliding forward in the chamber; it also serves to pull the fired case out of the chamber or the revolver barrel instead of an extractor groove . Such cartridges are characterized in metric designation with an "R", such as the 7 × 65 mm R .
literature
- Gerhard Bock: Modern handguns and their use . J. Neumann Publishing House, Neudamm 1911.
- Frank C. Barnes: Cartridges of the World . Krause Publications, Iola (Wisconsin) 2006, ISBN 978-0-89689-297-2 .
- George Madis: The Winchester Handbook , Copyright 1981 by George Madis, ISBN 0-910156-04-2 .