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The 6mm Story

by Jon R. Sundra   |  January 4th, 2011 0

Has the rise of rifle specialization dimmed the star of our smallest big game caliber?


I can remember like it was yesterday when the talk of the gun world was the .243 Winchester versus .244 Remington, and the “dual-purpose” rifle concept. Not that the idea of having a sporter-class rifle capable of taking varmints and deer with equal aplomb was a new idea back in 1955 when these two rounds were introduced. I mean, cartridges such as the .22 Savage Hi Power, .25-20 Winchester, .250 Savage and .257 Roberts preceded the 6mms by as much a half-century, as did the idea of hunting varmints and deer with the same rifle.

It’s just that the 6mm (.244 inch) was for all intents and purposes considered a new caliber, despite the fact that both Remington and Winchester chambered sporting rifles for the 6mm Lee Navy cartridge of 1895. It was hardly a stellar seller, though, and by 1935 factory ammo production had ceased.

Most old-timers probably remember the great .243/.244 debate that raged during the late 1950s and early ’60s. It was a time when gun magazines–which at that time were as new as the 6mms themselves–provided a platform for writers to argue the merits of one over the other.

And argue they did. You see, Remington thought its .244 to be primarily a long-range varmint cartridge and as such settled on offering 75- and 90-grain bullets in factory loads. Winchester, on the other hand, viewed its .243 to be more of a deer and antelope round and therefore went with 80- and 100-grain slugs.

Back in those days, the eastern woodchuck was far more synonymous with the word “varmint.” Today it’s different. Good ‘chuck country has diminished throughout the East, while prairie dog shooting has become an industry in itself. With the volume of shooting one can encounter on a good dog town, most experience shooters gravitate to lighter-recoiling .22 and .20 caliber cartridges. As we’ll see a bit later on, this has contributed to the decline of the 6mms.

Anyway, truth be told, the .244′s larger case was capable of imparting about 100 fps more velocity, all other things equal, than the .243, but since there was no common bullet weight offered in factory ammunition, it was an apples/oranges thing.

If it’s true what they say about perception being everything, the perception was that the .243 with its 100-grain bullet was an ideal deer load but the .244′s 90-grain bullet was not. Now normally that would not have presented a problem if you were a handloader contemplating getting a .244; you’d simply buy a box of 100-grain bullets and have at it. Trouble was, Remington chose a 1:12 twist for the .244 while Winchester went with the faster 1:10 needed to stabilize 100-grain spitzer bullets.

As it turned out, a 1:12 twist proved marginal for a 100-grain spitzer bullet if it wasn’t exiting at least close to nominal velocity. That’s why Sierra and Hornady quickly introduced 100-grain roundnose bullets in 6mm, but that didn’t help. After all, it was the high-velocity, flat-shooting attributes that attracted shooters to these high-stepping cartridges in the first place, and saddling the .244 with a roundnose bullet was akin to harnessing a race horse to a plow.

Actually, Remington changed the rate of twist in its Model 722 rifles shortly after the .244′s introduction, but it wasn’t publicized very well and was too late to change the public’s perception. Another factor that affected the .244′s destiny was the fact that handloading wasn’t as popular 50 years ago as it is today, and as a group, handloaders couldn’t commercially make or break a new cartridge.


The first commercial 6mm was the Lee-Navy of 1895 (left), but it was not very successful. Today’s crop of 6mms consists of (l. to r.): .240 Weatherby, 6mm Remington, .243 Winchester and .243 WSSM.

To make a long story short, the .243 Winchester went on to become an extremely successful cartridge while the .244 languished. Remington, however, refused to let what it knew to be an excellent cartridge die, and in 1963 it reintroduced the .244 as the “6mm Remington” in conjunction with a new 100-grain factory load that was claimed to exit at 3,190 fps.

That was at a time when the company was using 26-inch test barrels to establish factory ammo velocities. Once SAAMI decreed that 24-inch barrels be used to establish more realistic factory specs, velocity for the 100-grain bullet in the 6mm Remington was reduced to 3,100 fps (and 2,960 for the .243).

In my opinion, the .243 Winchester and .244/6mm Remington raised the accuracy standard for big game production rifles and ammunition for calibers larger than .224. With either caliber one could have reasonable expectations of finding a factory load that produced that magic one-inch group at 100 yards. It was still by no means common, but there’s no question in my mind that the 6mms set the accuracy bar a little higher for all larger calibers.

I was an early fan of the .24, and being the contrarian that I am and already a handloader at the time, I opted for the Remington. It was just after the .244 had been reintroduced as the 6mm Remington that I built a rifle using a commercial Santa Barbara Mauser action, which I had fitted with a 1:10-twist Douglas sporter-weight barrel.

I lived in Pennsylvania at the time and used that rifle with 75-grain Hornady’s extensively on groundhogs, and the rifle went on my first trips out West for mule deer and antelope–and even in Canada for black bear. All the big game was taken with one shot using either Hornady or Sierra 100-grain spitzers, so I was certainly pleased with it as both a varmint and a game rifle.

My longest shot was 330 paces across the Wyoming sagebrush at my first pronghorn buck; it dropped like a stone, but my shot was unintentionally high and I spined it, so that didn’t prove much. I did, however, find myself passing up shots that with more gun I might have taken. As much faith as I had in the caliber, I was a realist; I knew those little 100-grain bullets were running out of steam beyond the 300-yard mark.

It wasn’t until 13 years after their debuts that the .243 Winchester and 6mm Remington had any commercial competition. It came in 1968 from Roy Weatherby in the form of his .240 Weatherby Magnum, a cartridge based on a unique case having a rim/belt diameter the same as a .30-06. However, to form the belt, the case steps down .020 inch, so the actual body diameter of the .240 averages that much less its entire length.

The result is a
case that has slightly less powder capacity than the .30-06, but it’s more than enough to push 6mm bullets about 200 to 300 fps faster than the 6mm Remington and .243 Winchester, respectively. Being a proprietary cartridge, however, the .240 had little impact in the marketplace.


The .243 Winchester is still a strong seller, evidenced by Winchester’s new Super-X Power Max Bonded—which pushes its 100-grain bullet at 2,960 fps—and Hornady’s new Superformance load.

In the same class ballistically as the .240 Weatherby was the 6mm-284, a fairly popular wildcat based on the .284 Winchester, which debuted in 1963. In addition to the 6mm version, the .284′s rebated case was the basis for a whole family of wildcats that proliferated in the mid- to late 1960s in every caliber from .224 to .35. It, along with another wildcat, the 6mm-06, added another rung to the .24 caliber performance ladder.

More recently, of course, Winchester introduced a 6mm in its Winchester Super Short Magnum line. The .243 WSSM offers bullet weights in 100 (Power Point) and 95 grains (XP3 and Ballistic Silvertip). The latter leaves the muzzle at 3,150 fps and is still generating the 1,000 ft.-lbs. of energy necessary to kill a deer (and certainly a pronghorn) out to 400 yards.

Nevertheless, despite the significant increase in velocity the aforementioned magnum-class .24s provided, they were still 6mms, and therefore the perception was that only made them better deer and antelope cartridges but nothing more. That’s one of the reasons the 6mms have declined in popularity.

Another reason–and one that can’t be overemphasized–is that the “all-purpose” or “dual-purpose” rifle is not as popular a concept as it once was. There may be fewer hunters today than there were a half-century ago, but each of us owns more guns.

Today we have a mind-boggling number of new cartridges and rifles to choose from, and many of them are highly specialized. That’s because the savvy rifleman of today is less willing to compromise; he’s not looking for a “do-everything” rifle but rather one with specific features that make it better suited to a certain type of hunting.

That’s the kind of environment the 6mms find themselves in today. Yes, any .24 caliber sporter with a midrange variable scope aboard will make a good groundhog rifle, but a 26-inch heavy-barreled .22-250 with a high-powered scope makes a better one.

Yes, that same .24 just described will make a pretty good antelope or mule deer rifle, but with the high likelihood that you might be faced with a 400-yard shot across the windy plain, or to an adjacent mountain side, you’re going to want a little more gun.

That pretty much is the story of why my only current 6mm–a Ruger No. 1–has been relegated to the back of the gun cabinet, and I’ll bet I’m not alone. Besides, who wants to own just one rifle?

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