6.5mm in XIX century

Gentlemen,
is here any source or sources that discloses reasons why certain European powers went to 6.5mm rifle caliber in 19th century, as opposed to more common 7-8mm caliber?
I understand that in Japan main reasoning was that smaller stature of Japanese soldiers made firing of larger calibers uncomfortable for them, but does this apply as well to Italian, Greek, Norwegian, Dutch, Rumanian or Swedish soldiers of 1890s?

I can tell you a little about the Norwegian-Swedish 6,5x55:

Norwegiantesting of different calibers found that 6,5 mm had a good combination of flat trajectory, little recoil, and stable bullets. Norway switched to 6,5 mm from 10,15 Jarmann.

On the 23rd of April 1889 a “Rifle commmision for processing of the question of adopting a smaller caliber cartridge than 10,15 mm” took session to find a more suited caliber for the new Krag-Jørgensen receiver (which was experimented in in 10,15 mm in the start, and adopted by Denmark in 8x58RD and USA in .30-40).

They decided to procure and test the following rifles:
10,15 mm Jarmann rifle
10,15 mm Jarmann rifle rebored for jacketed projectiles
8 mm Swedish modified Remington rolling block rifle
8 mm Danish “Experimental Rifle #1” (Remington-Lee)
8 mm Danish “Experimental rifle #2” (Krag-Jørgensen)
8 mm modified Jarmann
8 mm modified Remington rollig block
7,6 mm Belgian Nagant rifle (?), eventually Jarmann and Remington in same cal if found to be acceptable
eventual other foreign guns

In the end they recommended further testing of 7,6 mm and even smaller calibers. After a short while the commision focused on trials with an 8 mm caliber cartridge. In February 1890 they recommended adopting the 8x58 RD Remington rolling block rifles, while they also said that tests in smaller caliber cartridges would be wise, as one likely could achieve better results with smokeless powder and small (7,6-6,5 mm) diameter bullets.

Rifles with barrels in calibers 8 mm, 7,5 mm, and 7 mm were specially built by Kongsberg for pressure, speed, and trajectory testing. 6,5 mm Mannlicher barrels for Italy were procured and also tested (these testbed rifles were modified Jarmann actions).

They found the following numbers while testing trajectory data:
Caliber: range out to which the bullet was in the same 1,8 m height/vertical span -
10,15 mm 438 m
8 mm 502 m
7,65 mm 512 m
6,5 mm 557 m

6,5 mm in the testbed achieved 691 m/s v0 while the others were between 600 - 680 m/s v0.

The committee found that 6,5 mm had the most pleasing results. There were certain attemps at 5 mm cartridges, but these were abandoned as they found 6,5 already had a high chamber pressure.

The considered rifles and ctrgs were in winter 1891-92 the following:
Austrian 8 mm Mannlicher
Portuguese 8 mm Kropatchek
German 8 mm Mauser-Spandau
Danish 8 mm Krag-Jørgensen
Belgian 8 mm Nagant
English 7,9 mm Lee-Speed
Swiss 7,5 mm Schmidt-Rubin
8 mm Marga
7,65 mm Mauser
6,5 mm Mannlicher (Dutch/Romanian)
Norwegian 7 mm Krag-Jørgensen

The models which were continued to be tested were:
Krag-Jørgensens latest models
Romanian Mannlicher pattern
Mauser
while the Schmidt-Rubin and Margas were to be considered as second choices.

Among the powders tested were Wettern powder, Margas, Blättchen, Norwegian Ballistitt, and Troisdorffer-powder. The powder acquistion was handled by the “Artillery board”.

At this point a Krag-Jørgensen rifle in 6,5 mm was test-shot and controlled for bore wear. The gun in question’s barrel opened up from 6,50 to 6,57 mm during testing (over 4000 rnds).

In summer of 92 they tested 6,5 vs 8 mm in various test, some following:
15 m range to test the importance of the position of the sights and shooting position
500-2000 meter tests to see the impact of rifling rotation imparted upon bullet (spin drift)
1500 m test to see wind impact on bullets
100 m test shooting into wood, sand, dirt, clay, and horse cadavers to see the different penetration and wound channels
300 and 1000 m tests to calculate sight heights

Experimental 6,5x57 cases were decided upon to hold a large enough charge of Ballistitt (Ballistite) powder. Jarmann rifles were converted to this 6,5x57 cartridge.
Trials eventually concluded that 6,5 was superior to 8 mm in regards of flatness and energy retention.
6,5 mm had a “flat trajectory” out to 579 m while 8 mm was 537 m. 6,5 mm was found to have a better precision/accuracy potential than 8 mm at the ranges tested.

After this process there was a lot of back-and-forth on mechanism type, sights, magazines, bullet shape and weight, etc.
The 1893 Norwegian commission found that 6,5 mm was the most suited caliber, no other countries used a smaller one, and one decided that a smaller one (such as 6,25 or 5 mm) would have a higher chamber pressure.

Krag designed a cartridge at this point which was 6,5x56,5 mm and most likely based on a “7 mm Roth Long” case. There is also a related cartridge in 6,5x55 mm with a semi-rim which is very similar to the 6,5x55 adopted in 1893/94. This has a connection to the Norwegian-Swedish rifle commitee of 1893 which would lead to Norway adopting the Krag-Jørgensen M/1894 in 6,5x55 and Swedish adopting their Mauser 96 pattern rifles and carbines. See BMF’s post below for more concise info.

The whole design and procurement process for the 6,5x55 and Krag-Jørgensen is very deeply covered in this book:
“Norwegian military rifles after 1867 - Karl Egil Hanevik”
ISBN 82-993143-1-3

Ole

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As for stature of Norwegian soldiers, here’s an interesting bit about the Norwegian license-made HK G3, designated AG-3 (automatgevær 3) in Norwegian use.
During testing of the rifle in 1963, prior to the Norwegian adoption, the Army’s Weapon-Technical Corps measured the arm length of 1500 conscripted soldiers, to find out if the original HK G3’s length of pull was long enough.

It was found that the Norwegian average soldier had longer arms than that of German soldiers, and thus Norwegian AG-3s are made with 2 cm longer stocks than the original German HK G3.

In Norwegian use, there were three stock lengths:
Original German stocks, issued to women and men with smaller builds
Original Norwegian stocks, regular issue
Original Norwegian stocks with a stock extender making it a little longer.

Ole

Thank you for the extremely detailed history of the development of the 6.5 x 55 cartridge. There is a lot of thought and careful experimentation that goes into the selection of caliber and firearm. (Although sometimes politics, place of origin, and other non-technical factors seem to be more important to the decision makers when some other countries adopted calibers/firearms.)

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I think every country would have preferred 6.5 mm due to the reduced ammunition weight. But the question was: Has 6.5 mm enough wounding power?
In the Netherlands, the answer at adoption time was yes, in Germany, for example, it was no.

After negative reports from (what is today) Indonesia, the Netherlands in 1910 launched an experimental “stopping powder” study, which in 1912 had the result of recommending a larger caliber.

Haneviks book is great and full of very interesting information. Too bad there’s no english version.
Ole: I feel the need to adress a couple of things from your post, that was a bit unclear. It was the norwegian army that conducted ballistic tests in the years 1891 - 92. The swedes entered the project when it was clear that 6,5 mm was the superior calibre. From then the two countries did paralell tests. The norwegian 6,5 mm trial cartridge from 1892 was rimless, while the swedes went with a rimmed version. When they started common trials, the swedes wanted a rimmed cartridge, and that was the reason for the norwegian semi-rimmed version. They wanted to meet the swedes half way. The cartridge was nicknamed the “unioncartridge”. The final 6,5x55 cartridge was designed by a norwegian / swedish commission in november 1893.

7mm Krag trial cartridge: http://www.kvf.no/vaapen.php?type=Ammo&weaponid=AMM0012

6,5x55 semirimmed: http://www.kvf.no/vaapen.php?type=Ammo&weaponid=AMM0013

https://forums.gunboards.com/showthread.php?368366-6-5mm-Jarmann-M-1892-and-early-experimental-6-5mm-cartridge

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Thanks, gentlemen
Lots of very interesting material there

I think every country would have preferred 6.5 mm due to the reduced ammunition weight. But the question was: Has 6.5 mm enough wounding power?
In the Netherlands, the answer at adoption time was yes, in Germany, for example, it was no.

After negative reports from (what is today) Indonesia, the Netherlands in 1910 launched an experimental “stopping powder” study, which in 1912 had the result of recommending a larger caliber.

The problem with most of the early 6.5 mm rounds is that they used round-nosed bullets which did not yaw much, but punched fairly small holes, making relatively minor wounds unless they hit something vital. Effectiveness was of course transformed by the discovery that pointed bullets, adopted for aerodynamic reasons, become unstable after impact, creating much larger wounds. The Japanese 6.5 mm pointed bullets were noted by US Army medics in WW2 as making wounds which could not be distinguished from those made by the 7.7 mm.

BMF, is the 7mm Krag a necked up 6.5x55 ?

Thanks for the correction. I was writing partly from memory and partly what I found in the book.
I removed the paragraphs on the rim/semi-rim/rimless case as it’s not completely related to the choice of 6,5 mm caliber.

Ole

The 6,5x55 as we know it now came to be in 1893, so the 7 mm trial cartridge of 1891 was part of caliber trials eventually leading to the 6,5x55.

The book I mentioned mentions “short” and “long” Roth 7 mm cases being used as basis for several cals. during the trials.

Ole