April 04, 2019
In the last two decades we’ve see a resurgence of 6.5mm (.26 caliber) rifle cartridges, and many are used for demanding match shooting where accuracy is everything. It is fitting that an old foreign military cartridge that introduced many U.S. sportsmen to this bore diameter is also highly respected for its accuracy. The 6.5x55mm Swedish Mauser cartridge debuted around 1893 for the Swedish variations of the M1893 Mauser rifle. That makes it slightly older than the .30-30 Winchester!
The 6.5x55mm became the darling of Scandinavian sport shooters, prized for both its performance on game and its accuracy in matches. Given its age, the “Swede” has remarkably modern proportions. Its 25-degree shoulder angle is steeper than most of its contemporaries, contributing to the ageless appearance. I was struck by the physical and performance similarities to the recent 6.5 Creedmoor. The Creedmoor has a slightly steeper shoulder angle and a shorter 49mm case for AR actions, but I think I see a resemblance.
The Swede case does not have a “standard” base diameter. Its European 6.5mm contemporaries often had the 0.445- to 0.455-inch base diameter found in many Mannlicher cartridges. Mauser cartridges from that time, like the 8x57mm and 7.65x53mm, pioneered the 0.470- to 0.473-inch base that we see so often today; we call it a “.30-06 head,” but it predates our venerable service cartridge. At 0.480 inch, the Swede’s base makes it an oddball. The Swedish case is not easy to form using more common cases, but ready-made cases and factory ammo are easier to find now more than ever before.
U.S. shooters had few opportunities to experience 6.5mm performance between the World Wars. There were a few imported Mannlicher-Schönauer sporting rifles chambered for the less powerful 6.5x54mm cartridge, and some rare proprietary .256 Newton rifles (basically a 6.5-06). Swedish Mausers began to show up in numbers after World War II, and the little Model 94 carbines were especially popular as they could be used for hunting with very little customization should the buyer’s budget be tight.
It is a tribute to the usefulness of this cartridge that it achieved significant acceptance among U.S. shooters with essentially one source of ammunition and cases: Norma. It was not until near the end of the 20th century that major U.S. ammomakers offered 6.5x55mm ammunition and cases.
Much of the Swede’s hunting success has been attributed to long bullets at modest velocity, and I have to agree. That’s a good combination for deep penetration. Europeans still use 6.5x55mm ammo on big game, loaded with bullets weighing between roughly 155 to 160 grains. The 140-grain loads are the most common in the United States, and factory velocities run from about 2,550 to 2,735 fps.
For U.S. hunters the 140-grain bullet is the all-around weight for the 6.5 Swede. Its sectional density of 0.287 matches a 160-grain 7mm bullet and exceeds that of a 180-grain .30-caliber bullet. The high-tech construction of many new bullet styles means today’s 140-grainers typically out-penetrate the heavier conventional 6.5mm bullets popular with our European counterparts seeking larger game.
The U.S. industry has kept 6.5x55mm pressures conservative—the official assignment for the maximum average pressure is 51,000 psi, the same as the 7mm Mauser. After Ruger, Winchester, and Remington all introduced modern bolt rifles chambered for 6.5x55mm in the 1990s, we did a complete reshoot of Swede data on the latest transducer equipment, ultimately showing two levels of handloads in the Speer Reloading Manual #14.
We set loads in the first set to SAAMI guidelines for “two-lug” Mausers like the M94 and M96 Swedish service carbines and rifles. The second set was for the newly manufactured commercial U.S. rifles and Mauser 98k models rebarreled by Schultz & Larsen to 6.5x55mm. For these we set pressures at 58,000 psi, closer to European pressures and the same as the .257 Roberts +P. This drove 140-grain hunting bullets to the mid-2,600 fps range from a 24-inch barrel.
Some of today’s 6.5 Swede factory ammo using non-canister propellants can post this sort of velocity within the conservative SAAMI pressure limit. Hornady has a 140-grain Superformance load that is rated at 2,700 fps, the same as the 6.5 Creedmoor. Other brands have loads at 2,650 fps.
Although the compact case suggests otherwise, the Swede thrives on slower-burning propellants. In those tests in 2006, we saw best velocities from Alliant Reloder 22 and Reloder 19 with 140-grain bullets, and slow propellants introduced after I retired in 2007 continue that trend.
Lighter hunting bullets are useful for smaller deer species, and we were able to push some varmint-weight bullets to 3,400 fps from a 24-inch barrel. However, this brings up the only real quirk in this otherwise well-behaved cartridge.
Both SAAMI and CIP chamber drawings for the 6.5 Swede show the legacy of heavy bullets: The chamber throat length is 0.5551 inch. That is by far the most of any U.S. 6.5mm/.26-caliber cartridge with conventional throating.
What does this mean for reloaders? A short bullet seated too deeply will experience a long jump before engaging the rifling. In addition to ballistic inconsistencies, this will affect accuracy. Factory ammo compensates for this with bullet length and profile choices; the reloader can adjust cartridge overall length (COL) as well.
The maximum COL for the Swede is a generous 3.150 inches, and handloaders should take advantage of it. Bullets under 140 grains should be seated as long as possible while still keeping about 0.20 to 0.25 inch of shank in the case neck. The closer to maximum safe pressures you are, the better chance a short bullet has of gracefully dealing with throat jump.
If you need reduced-recoil handloads, do it with 140-grain bullets to improve ballistic efficiency and fit chamber throats. Hodgdon has information on making effective reduced loads using H4895 propellant.
Is it likely that the old Swede will see another resurgence? Despite its capability of greater performance given a higher pressure limit, probably not. The rapid increase in new 6.5mm cartridges over the last 15 years gives the average shooter more than enough choice. However, let’s not forget the one that opened the door.