H.K.H. Kronprinsen bestemte at Jarmann-geværet med fast magasin skulle antas for bruk i det norske infanteriet. Det skulle derimot gå lang tid før modellgeværene ble approbert, dette skjedde ikke før 8. april 1884. Jarmanns gevær var... Read more ...
Jarmann-geværet ble approbert
H.K.H. Kronprinsen bestemte at Jarmann-geværet med fast magasin skulle antas for bruk i det norske infanteriet. Det skulle derimot gå lang tid før modellgeværene ble approbert, dette skjedde ikke før 8. april 1884.
Jarmanns gevær var opprinnelig et enkeltskuddsgevær, og dette geværet ble utlevert til tropper for utprøving allerede fra 1878. Modellbetegnelsene som vanligvis blir brukt kan virke noe forvirrende. Jarmanngeværet med fast rørmagasin under forskjeftet ble egentlig approbert i 1881, men det var først med en approbasjon i 1884 at det formelle grunnlaget for geværets modellbetegnelse ble lagt. Den første modellen kalles derfor M/1884. M/1884 ble forbedret av en approbasjon i 1887 der ca. 15 mindre endringer ble gjort på geværet, og det kan derfor være grunnlag for en M/1887. Andre mindre endringer ble approbert i 1888, 1889 og 1890.
Geværet kan brukes både som enkeltskudds- og repetergevær. Bruksmåten kan reguleres ved hjelp av en omstiller på låskassens venstre side. Flerskuddsmekanismen fungerer på følgende måte: en spiralfjær sørger for å dytte patronene bakover i rørmagasinet. Når sluttstykket føres i bakre stilling trekkes den skutte patronen ut av kammeret og kastes ut. På samme tid senkes patronheisen, og en ny patron presses ut på heisen. Når sluttstykket føres fremover heises patronen opp og når støtbunnen treffer patronen i bakkant føres patronen inn i kammeret.
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It has long been an established fact that so called multiple discharges or chainfires in percussion revolvers originates from the chamber mouth of the cylinder. But, is this a myth, or are there other explanations? This article seeks to prove that multiple discharges may just as well be caused by loose fitting caps.
Published: 11. September 2008 by Øyvind Flatnes.
Edited: 12. September 2008.
Norway was one of the first countries in the world, perhaps even the first, which adopted a repeating bolt action rifle for the armed forces. The rifle was invented by the Norwegian engineer Jacob Smith Jarmann, and was adopted in 1884. However, the Jarmann rifle was not the first magazine rifle that had been in use in by the military in Norway. The navy had used the rather clumpy Krag-Petersson rifle since 1876, but with this rifle the shooter had to help with the fingers to manually load a new cartridge in the chamber. The Krag-Petersson rifle used the same rimfire ammunition as the 12 mm Remington rolling block rifle.
Find out more!
You can read more about the Norwegian Jarmann and Krag-Petersson, as well as other early military repeating black powder rifles in the brand new book From Musket to Metallic Cartridge: A Practical History of Black Powder Firearms.
The Jarmann rifle can be used as both a single shot and repeating rifle. You can switch from single shot to repeating mode, or the other way around, by turning the fire selector on the left side of the barrel 180 degrees forward or backwards. The repeating action works in the following way: A coil spring pushes the cartridges backwards in the tubular magazine. When the bolt is moved backwards the empty cartridge is extracted from the chamber. At the same time the cartridge elevator is lowered and a new cartridge is forced onto the elevator by the coil spring in the magazine. When the bolt is moved forward the elevator lifts the cartridge is lifted by the elevator and when the bolt hits the cartridge base it is pushed into the chamber.
Today the Jarmann rifle is extremely rare despite the fact that about 30 000 of them were made in Norway and 1500 in Sweden. Where they all have disappeared no one seems to have the exact answer, but a large amount was destroyed by the Nazis during the World War II occupation. A great deal was also converted to harpoon guns (rescue guns). The civilian market was not very interested in the Jarmann rifle when the armed forces tried to sell them when they were obsolete. One of the main reasons was that it was hopelessly inferior to the new Krag-Jørgensen rifle.
The pictures show the fire selector that allows the shooter to switch between single shot and repeating fire.
On the picture to the left single shot is selected, while on the picture to the right repeating fire is selected.
The picture series above shows how the repeating mechanism works. When the bolt is moved backwards a new cartridge is forced onto the cartridge elevator by the coil spring in the magazine (picture 1). When the bolt is moved forward the cartridge is lifted by the elevator (picture 2), and the cartridge is inserted into the chamber (picture 3).
The magazine could take eight centre-fire bottleneck cartridges. The ammunition went through several changes:
The ammunition of 1878 was initially meant for the Jarmann single shot rifle. The lead bullet weighed 21.85 grams (337 grains), and the diameter was 10.03 mm before patching. After patching the diameter was increased to 10.30 mm. The load was 4.46 grams (68.8 grains) of black powder.
The modified cartridge
After the transition from single-shot rifle to repeating rifle it became clear that the muzzle velocity of 474.5 m/s dropped to 465.5 m/s measured 25 alen from the muzzle. It was therefore decided to increase the load to 5 grams (77.1 grams) in 1883 and later to 5.1 grams (78.7 grains) in 1885.
When it was complained that the paper stuck to the bullet and ruined the accuracy extensive ammunition trials were started. The construction committee of 1889 writes that:
'With wads of carton and wax-turpentine wads, in addition to vaseline (petroleum jelly) on the projectile we have during the last trials gotten so good results that the construction committee in accordance with the gun commission's observations suggests that:
1. The wad is to consist of a carton directly on top of the powder, and on top of that a 3.5 to 4.8 mm thick wad consisting of 3 parts wax and 2 parts turpentine.
2. That the projectile is given a coat of melted vaseline grease of which the temperature is not to exceed 85° C. The plane section of the bullet is to be wiped free of grease.
3. It is instituted inquiries of the ammunition of the sort mentioned above after it has been stored a longer period of time, for example, one year.
The commission is aware that the above mentioned suggested wad and grease may not guarantee that the paper in the future will follow the projectile and cause irregularities in the trajectory, but as these irregularities have occurred on distances over 1000 metres, and that our trials seems to show that it these days is not possible to achieve better results, we find it not adequate to perform more trials. Accuracy on the greater distances that suits these days demands is probably only achievable with metal jacketed bullets'
Transition to smokeless powder
Metal jacketed bullets were introduced in 1893 and at that time the black powder load was replaced with a load of smokeless ballistite powder. This increased the muzzle velocity to 490-510 m/s measured 25 metres from the muzzle. This resulted in a flatter trajectory, but the sight settings did not fit the new trajectory. The sight settings were never fixed, probably because the Krag-Jørgensen rifle was on its way to replace the Jarmann rifle. The diameter of the metal jacketed bullet was 10.4 mm.
The picture above (top right) shows an original calibre 10.15 x 61 Jarmann cartridge loaded with ballistite powder and a steel jacketed bullet.
Part two of this article will deal with the practical use of the Jarmann rifle.