Swedish Jarmann rifle No. 1024.

Kongsberg Model 28 harpoon gun.

Open bolt.

Jarmann bolt.

Disassembled bolt.

Nose band with front sight.

Swedish rear sight.

The rear sight ready for long range shooting. Note Colonel Holkin's volley sight for even longer ranges on the left-hand side.

Volley sight mounted on the barrel band.

Barrel, magazine and trigger assembly.

Trigger and trigger spring.

Jarmann bullet mould patterned after the original made by Steve Brooks.

Bullets cast with the Brooks mould.

Jarmann ammunition hot off the press.

The newly made shooting sling.

The first shots with the Brooks bullet.

A while back I came across an original Swedish Jarmann repeating rifle in near perfect condition. Only 1,500 Swedish Jarmann rifles were manufactured; 500 two-band rifles that were issued to the Swedish Royal Life Guard (160), the volunteer infantry school in Karlsborg (300) and the shooting school in Rosersberg (40), and 1000 three-band rifles for the Swedish Navy. Even though Norway produced about 30,000 Jarmann rifles at the Kongsberg Armoury, the Swedish are far cheaper and easier to get hold of than the Norwegian. This is due to the fact that most of the Norwegian rifles were either destroyed by the Germans during World War II or converted to harpoon and rescue rifles after the Krag-Jørgensen rifle had replaced the Jarmann.

The Norwegian and Swedish Jarmann rifles were chambered for the 10.15mm (.40") union cartridge commonly known as the 10.15x61 Jarmann. Only minor differences separate the Norwegian and Swedish rifles. All the Norwegian rifles have two bands and uses band springs to keep the rear barrel band in place as opposed to the Swedish that utilise screws. As well as different rear sights, the Swedish rifles have brass inspection lids on the stock under the action secured by two screws which is useful if you remove the bolt while the rifle is in repeating mode. Another difference is that the front sight of the Norwegian rifles is attached to the barrel, while on the Swedish it is attached to the barrel band.

Test shooting

The Jarmann rifle which was featured in part one and part two in this series had a new replacement barrel from Kongsberg in Norway and a bolt from Carl Gustaf Stads Gevärsfaktori in Sweden. The stock was new. The accuracy was excellent – especially with swaged paper-patched bullets – but these bullets are unfortunately no longer available.

However, I tested the rifle with a grease grooved bullet from a svartkrutt.net group buy in 2008. The round nose bullet has two broad grease grooves, but due to the nose shape it cannot be used in the tubular magazine. The bullet weight is 337 grains, which is identical to that of the original.

The chambers of my two Jarmann rifles were quite different, which is not uncommon with Jarmann rifles. In an article published in VåpenjournalenNo. 4 1998 the late Norwegian gun writer Svein Solli claimed that the headspace could differ as much as 4mm (.157") from rifle to rifle. The Bertram cases that had previously been fired in the Norwegian chamber would not chamber in the Swedish, and as it turned out the CH4D sizing was too long to force the shoulder sufficiently backwards. The solution was to remove some metal in the bottom of the die, after which the die worked perfectly.

As you can see in part 2 the restocked rifle shot very well with 70 grains of Wano PP. Since Swiss powder usually performs better, I decided to give Swiss #4 (1.4 Fg) a try. The first cartridges were loaded with 70 grains which filled the cases slightly above the shoulder. I used semolina as filler. Since the cartridges were meant for testing and make sure the gun fired, I skipped paper wads and compression.

First time failure

The first time I tried the rifle the firing pin only made a small indent in the Federal Magnum primer, but not enough to set it off. I suspected the reason was too much headspace, as was a problem with my other Jarmann. The reason is that the original brass had a slightly thicker rim compared to Bertram's brass. With the former rifle I had to make a thin brass washer which was threaded over the cartridge to make an artificial thicker rim. Upon ignition the shoulder was pushed forward and in subsequent loadings the cartridge chambered on the shoulder. But even with the washer the rifle refused to go off.

Upon pulling the trigger it seemed that something interfered with the firing pin in its forward motion. A closer inspection revealed that some previous owner had been too eager with a file, probably in an attempt to loosen the trigger pull. The filing had resulted in a half cock notch that was higher than the full cock notch. As a consequence the half-cock notch interfered with the sear on its way forward and lost some of its force. The error was corrected by a gunsmith, after which it worked flawlessly.

The first test was fired at 50m with the group buy bullet. With a six o'clock hold and by using a blow tube between each shot, all shots hit the black of the UIT 50 pistol target with the lowest 300m sight setting. Most shots ended up at 2 o'clock. At 100m the bullets hit below the target with the same sight settings. After the first test I found out two things: The trigger pull was way too hard with too much creep – and I needed a target sling.

Making a target sling is easy. To make an all-leather target sling, see the article about making slings. Based on the Norwegian Remington rolling block and kammerlader slings, I simply add a number of extra openings to make the sling adjustable.

The trigger pull improved slightly after the screw that puts tension on the trigger spring was released. This is a quick fix and the problem needs to be addressed with a file for a permanent solution.

Custom made bullet mould

After having made sure that the rifle worked it was time to load a batch of proper cartridges. Since the original load utilised a paper-patched bullet I had Steve Brooks make me a copy of the smooth-sided original 337 grain bullet. Even though the nose differs slightly from the original, the rest of the bullet conforms closely to the original. As per the original it has a small cup base and the diameter is 10.03mm (.395") naked and to conform to the original it needs to the paper patched to 10.30mm (.406"). The high quality mould has an adjustable base plug which allows me to adjust the length of the bullet. Like all other Brooks moulds it is a dream to cast with.

Although I would have preferred to cast the bullets from a 1:30 tin/lead alloy, the first bullets were cast with pure lead due to lack of tin. The 10.03mm diameter corresponds to the bore diameter of the barrel. In an attempt to replicate the original charge as closely as possible, the bullets were patched to 10.30mm which is close to the rifling diameter. To achieve this I used four wraps of Seth Cole's 55W sketch paper. Previous tests have shown that several wraps of thin paper often produce better accuracy compared to several wraps of thicker paper. The bullets were lightly crimped to the case.

Brass

I had about 30 new Bertram cases, but it was worrying to see that a case neck was already split in the box, and another split in the expander die. I have never had problems with Bertram brass previously, but I have heard many others that have experience problems with cracked cases. The brass was properly annealed before fire forming in an attempt to make the brass softer and extend the case life.

Bertram has now fixed his 10.15x61 Jarmann brass, and it now has a thicker rim. However, my brass was from the old batch and because of the thin rim I had to use the washer during the fire forming to allow the shoulder to blow forward and prevent the primer from protruding out of the primer pocket upon firing.

During the first test it seemed that the barrel fouled more than usual, so I tried 73 grains of Swiss #3 (FFg) instead. The load was poured slowly through a 24" funnel and compressed in a .40 calibre powder compression die. I used .40 calibre cardboard wads punched with a press mounted wad punch made by Fred Cornell. The wads were slightly oversize, but after sizing in a .401 Lee push through sizing die they fit perfectly. One wad was placed on top of the powder before compressing, followed by a SPG grease cookie and a new wad.

First test with paper-patched bullets

Knowing that the fire forming possibly may affect accuracy, I set up a UIT 50m pistol target at 50m and used the new sling as support. I cleaned between each shot from the muzzle with one damp patch followed by one dry. The first 13 shots from the prone position with sling support went tolerably well. The vertical spread was OK, while the target showed signs of horizontal stringing. The horizontal stringing may be caused by inconsistent cheek contact, new cases, sight picture, too soft bullets or the load. Or simply poor shooting. Anyway, the final result was 91 points with the ten best shots counting. Not too bad, but it is bound to improve!

An identical test was carried out with the remaining new cases with the same load and bullet. This time I tried to get the shots into the X ring, which turned out to be more difficult than expected. The first shots hit a bit high, but with a lower hold it hit too low. I never managed to hit the ten and with a bunch of counting eights and nines it ended up with 86 points.

None of the Bertram cases cracked, by the way.

This article will be updated with new range reports as the shooting progresses.