Super Six

For effective hunting rifles, don’t rule out the 6mm

By: Wayne Van Zwoll 

You don’t hear much about 6mm cartridges these days. More-powerful rounds get most of the press, and mag­num cases don’t mate easily with .243 bullets. Necking a .300 Remington Ultra Mag or a .30-378 Weatherby to .243 has little to recommend it. Even the short magnums have more capacity than can be used efficiently behind a 6mm bullet. As for standard hulls, we’ve already “sixed” almost all of them. The .243 Winchester is an altered .308 Winchester, and the 6mm Remington a necked-down 7x57 Mauser. You’ll find few 6mm-06s on used-gun racks, but Weatherby’s .240 has essentially the same case volume. Wildcatters have put the 6mm-.250 Savage on the charts as the 6mm Donaldson (30-degree shoulder) and the 6mm International (with the shoulder pushed back to reduce case capacity). 

My field experience with the vari­ous sixes is pretty limited. Long ago I owned a 722 Remington in .244 Remington, a cartridge that appeared in 1955. The 722 had a 1-in-12 twist that stabilized bullets as heavy as 85 grains but was reported marginal with 100-grain spitzers. Winchester’s .243, which came along the same year, was cham­bered in barrels bored 1-in-10. Most hunters who bought 6mms, it seemed, wanted to shoot deer, not just ‘chucks and prairie dogs. Partly because the press claimed inadequate twist for heavy bullets in .244s and partly because Model 70s were available in .243, the Winchester round became more popular.   

In 1963, with the advent of its Model 700, Remington adopted a 1-in-10 twist in 6mm barrels and renamed the .244. As the 6mm Remington, it has fared better at market. If lion’s round has a fault, it’s in the parent case. The 7x57 is a centenarian cartridge that’s hard not to like—in Mauser rifles. You see, Paul Mauser designed his famous 1898 action around the 57mm hull. It’s longer than the 51mm case of the .308 Winchester, shorter than the .30-06 Springfield. To fit cartridges with 57mm brass into an action built around the .308, you have to seat bullets deep, reducing usable case volume and velocity. Short actions commonly used in 6mm and .243 rifles give no advan­tage to the longer 6mm Remington case. In long actions, the 6mm can be hand loaded to significantly higher speeds. But with a long action, why not chamber a .25-06 Remington? 

Or, if you must have a 6mm, why not try the .240 Hawk? 

The Hawk line was developed by Bob Fulton of Glenrock, Wyoming, and Fred Zeglin (www.z-hat.com) of nearby Casper. It’s based on the .30-06 case, with the shoulder blown forward and given a 25-degree slant. When I first met Zeglin years ago, the unassuming young man had built only a couple of rifles with Hawk chambers. One was a .358 for hunting partner Gradon Snapp. Snapp praised his .358 Hawk, claiming almost as much horsepower as the .358 Norma Magnum with 200-grain bullets at 2,800 fps. 

A 6mm wasn’t on Zeglin’s agenda then. The big case was better suited to huskier bullets. He built a .411 for me on a commercial Mauser action, fitting it with a Douglas barrel, a stick of curly maple and Ashley iron sights. Full-power loads with 300-grain bullets reached 2,500 fps, matching the .375 H&H and exceeding the punch of many traditional “elephant” cartridges. 

Zeglin eventually necked the Hawk case to .243. “What would you need that for?” I asked. A .240 on a bigger case than the standard ‘06 seemed  about as useful as a rocket-powered Yugo. “Overbore” by any definition, the .240’s ratio of case to bore volume all but equals that of the .244 Belted Rimless Holland & Holland Magnum, a necked-down .300 H&H introduced in 1955. 

Zeglin grinned. “What color do you want the stock?” 

Zeglin built the rifle on a Model 700 Remington action, installing a 28-inch Douglas octagon barrel heavy enough to anchor a yacht. The H-S Precision stock, painted red on special order, had clean lines and a good feel. A Weaver 6-20x40 Grand Slam scope in Talley rings completed the outfit. 

My first two shots from the 6mm Hawk slipped into one hole. Subsequent rounds clustered close by. Only bullets heavier than 85 grains failed to shoot inside 3/4 inch. That was predictable. Zeglin and I had agreed that this would be a varmint rifle. The 1-in-i 4 rifling twist was tailored to light­weight bullets. 

I was especially impressed with the .240’s metal finish, a satin blue by Phil Filing (307-436-2330, www.gunbIuing.com), who has lived in Glenrock for about a decade. “It’s a Teflon treatment,” Filing told me, ‘a baked-on finish That’s really more durable than blue.” It costs just a little more and is offered in five colors. Also, it bonds to any metal alloy. “The surface must have some texture,” Filing said. “We bead-blast­ed this rifle with aluminum oxide; it’s as fine as baking soda- Some companies use coarse glass beads that make the surface rougher than I prefer.” Filing finishes all Talley mounts. “Talley’s shop is next door,” he said, smiling. “We don’t waste money shipping.” 

The 240 Hawk holds a little more powder than the flat-shooting 240 Weatherby, which kicks 90-grain bullets downrange at 3,500 fps. Zeglin antici­pated 4000 fps with 60-grain bullets. “Maybe you can do even better,” he said as we tossed the rifle in my Suzuki. It sounded like a challenge. 

I started conservatively, my first loads nudging bullets along at idle. The first hint of trouble came with an 80-grain bullet clocking 3,591 fps ahead of 54 grains of Winchester 760. The bolt opened easily enough, but the primer was gone. I fired again and got a cracked case. Excess headspace, I thought. So it proved to be. I found the problem in the die setting. The custom dies were a bit too short for a “kiss fit” at the top of the ram stroke. In other words, full-length resizing reduced head-to-shoulder measure to below spec. So when the striker hit the primer, it drove the too-short case deeper into the chamber. Expanding gas inside the case ironed the pliable front of the case to the chamber walls while kicking back against the primer and head. Separations and lost primers resulted. Adjusting the die was easy. I just fined a fired case onto the ram at the top of its stroke and turned down the die until it contacted the case. Then I lowered the ram and gave the die an eighth of a turn down. I ran the case up again and checked the fit in the chamber, repeat­ing the routine until the bolt closed easily but snugly on the case. 

Groups with lightweight bullets at high speed stayed around 3/4 inch. And there’s not much need for a 100-grain bullet in a 6mm. Some hunters will dis­agree. But 85-grain bullets driven into the forward ribs of deer-size animals kill like lightning. The blistering speed of the .240 Hawk can make long shots easier, partly because you’ll use less holdover, more importantly because they’ll be less affected by wind—which, unlike gravity, varies in its effect. 

Sure, this Hawk is inefficient. So is an F-16. Sometimes performance mat­ters most. Fred Zeglin keeps busy these days building takedown rifles—from Model 95 lever-action Winchesters to Model 70s. But I’ll long remember that first 4,000-fps reading from an 80-grain bullet.... 

.240 Hawk First Round

I had no more problems with cases. Here are a few cream-puff loads for the .240 Hawk.  

.240 Hawk Second Round 

My second round of loads for the .240 Hawk was more ambitious, because I knew what to expect of the powders. Even with throat-burning acceleration, the long, heavy barrel kept recoil and muzzle jump down. Here’s a short list of loads that delivered super performance. Approach them with caution! 

   Reprinted here by permission of Harris Publishing, Deer and Big Game Riles 2003