Wildcatting the .284 Winchester

Wildcatting the .284 Winchester

Long-range shooters and wildcatters have kept the .284 alive.

While experience in the benchrest field has led to the modern mantra "Short and fat is where it's at," this was not always the case.


Along about 1999, after considerable prompting by the late Roger Johnston and with technical advice from this author, Norma standardized the 6.5-284, which had been a wildcat for decades. Roger's epiphany is one of those revelations that, in retrospect, is quite obvious. Since so many wildcatters and long-range target shooters were using the .284 Winchester case as a basis for various wildcat chamberings, particularly the 6.5mm, why not standardize a factory version?


History of the .284 is quite frustrating to those who know it well. Winchester's goal, circa 1963, was parallel to its creation of the .300 WSM--a short-action chambering that essentially duplicates .300 Winchester Magnum ballistics. When Winchester introduced the .284, the intention was to create a short-action chambering that would essentially duplicate .270 Winchester ballistics. Despite what has been written to the contrary, Winchester was 100 percent successful in that endeavor; when compared to the .270, the .284 launched bullets of comparable weight slightly faster. Nevertheless, as soon as the newness wore off, several gunwriting pundits of the day set about to eradicate what was clearly a superior cartridge design.

We can speculate the reason thusly: Those writers were clearly of the bolt-action-elitist genre, and, as such, they could find no value in any short-action chambering. Proof of this stems from examination of some of their arguments. I recall one author who decried the .284 because it would not launch 175-grain spitzers as fast as the .270 would--if only one could get such bullets for the .270.


Meanwhile, despite such ill-founded badmouthing, the .284 hung on. While it has been occasionally factory chambered in various rifles, the chief reason for its survival has always been wildcatting. For those who do not feel that they need magnum energy levels, the .284 is a fine case for wildcatting to all neck sizes from 6mm to .416. While it has been necked to .22, the results were quite disappointing, due to very short barrel life. On the other end, beyond .375, shoulder width becomes insufficient for proper headspace control. At .416 it is quite helpful, and desirable, to reduce body taper to Ackley specification, which widens the shoulder about 33 percent.

The .284 and some of its wildcat offspring, left-to-right: 6mm-284, 6.5mm-284, .284 Winchester, .30-284, .338-284, .375-284.

The 6mm-284 is most easily created by necking down the 6.5mm-284 Norma case, which is a direct conversion. However, it is possible to neck down the .284 Winchester case. When combined with heavy (95-, 105- or 107-grain) VLD target bullets, this number produces spectacular long-range ballistics and has been used successfully in 1,000-yard target matches. However, a more likely application is long-range varminting. With slower-twist barrels and lighter bullets, the 6mm-284 is capable of spectacular kills at unusually long ranges. For example, with a 26-inch barrel, it easily launches 70-grain moly-plated Nosler Ballistic Tip bullets at 3,900 fps. With a well-built gun capable of launching this bullet with sub-1/4-MOA accuracy, very long-range hits on vermin are completely feasible.

Perhaps the best known of the .284 wildcats is the .25-284. This number duplicates .25-06 performance but in a shorter case with a better basic configuration. All else being equal, a shorter, fatter case is a straighter case, and it also produces superior internal ballistic consistency--these are the main reasons that short, fat cases now dominate the benchrest game.

By increasing bore size only 0.007 inch, we come to the now-standard (factory-loaded) 6.5-284 Norma. With availability of useful bullets ranging from 85 grains to 160 grains, the 6.5-284 has a lot to offer varminters, big-game hunters and long-range target shooters. Given a 26-inch tube, this number easily launches moly-plated 142-grain Sierra MatchKings at 3,150 fps. Obviously, similar-weight hunting bullets at this velocity are capable for most North American hunting.

The next-likely bore size is .30 caliber. Here we have a short-action cartridge that essentially duplicates .30-06 performance with medium-weight bullets. Moreover, when chambered in a long-action rifle, it can significantly exceed .30-06 performance with bullets heavier than about 165 grains.

When we jump to .338 bore size, things get very interesting. Bullet selection is large, and, with moderate-weight bullets, this wildcat makes one of the better elk chamberings for those who cannot tolerate significant recoil. It will launch 225-grain bullets at nearly 2,700 fps and is therefore capable of delivering significant energy to targets out to about 300 yards with no sight correction when a 225-yard zero is applied.

The .35-caliber version duplicates the .35 Whelen but again in a short-action case. To me, a far more interesting version is the .375-284. With a wide selection of good bullets, this is a serious dangerous-game alternative. Chambered in a long-action rifle, it comes within a few hundred fps of the .375 H&H but generates far less recoil due to using a much smaller propellant charge.

As noted before, the .416-284 wildcat is possible, but it is better applied to the Ackley Improved version of this case. My series of .284 wildcats, developed for the Model 99 Savage, combines the Ackley case taper with the original .284 shoulder angle (35 degrees) instead of the steeper (40-degree) Ackley shoulder. The main advantage with my series of wildcats is use of the standard .284 headspace gauge. Compared to the 40-degree shoulder, difference in usable capacity is insignificant. By reducing body taper to Ackley's specification, regardless of neck size used, one increases usable case capacity about two grains, which seems worthwhile, particularly in bore sizes larger than 6mm.

The single complaint against the .284 is the rebated rim. In some types of rifles, this can cause a bit of difficulty for the gunsmith. It makes proper magazine lip configuration a bit more critical--poorly designed feed lips can result in the bolt overriding the next round, rather than picking it up. While a real consideration, it is the trade-off for allowing use of a 0.50-inch-diameter case with the conventional 0.47-inch-diameter bolt face. Moreover, this is not a serious problem when the gunsmith knows what he is doing.

Since the .284 is one of my all-time favorite factory cartridges, it does my heart good to see it regaining popularity through standardization of the 6.5mm version by Norma. It is worth noting that the most recent batch of Norma 6.5-284 cases that I have tested is particularly good as to concentricity and mass consistency.

As a related aside, the .376 Steyr (cases available from Hornady) has approximately the same base diameter as the .284 but is longer and has a conventional rim. When converted to the Ackley Improved configuration, capacity of this number is essentially identical to the conventional belted magnum, but it loads into and feeds out of a magazine far more smoothly.

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