Weatherby’s .30-378: The Race Is On For More Velocity!

by Layne Simpson

Capable of pushing a 180-grain .30-caliber bullet to 3,500 fps+ at the muzzle, the first .30-378 production rifle/ammunition combo puts Weatherby out front in the velocity race.

Weatherby’s recent domestication of the old .30-378 Magnum wildcat is a good example of persistence being rewarded. In the past I had on a number of occasions tried to convince Ed Weatherby that the time had come for his company to push ahead of the pack in the velocity race, just like his father Roy had done in the 1940s. Eventually, in 1992, I received a Mark V action from Ed with a note requesting that I put together a rifle in .30-378 Magnum. He wanted to know about accuracy of the rifle and how fast the cartridge would run.

I forwarded the Mark V action to gunsmith Kenny Jarrett who fitted it with one of his 26-inch, match-grade barrels and a Clifton synthetic stock. Its performance exceeded my expectations. I mentioned that rifle in the October 1993 issue of Shooting Times and predicted that if Weatherby did decide to introduce the .30-378 chambering, it would be in a new super-accurate variation of the Mark V rifle called Accumark.

There was more prodding on my part. During a 1994 caribou hunt in Alaska with Ed Weatherby and Brad Ruddell, also of Weatherby, I reminded them that time was awasting on the .30-378 Magnum project.

As another way of keeping the fire burning hot underfoot, Weatherby’s introduction of a rifle in .30-378 and factory ammo for it had, on a couple of occasions, been one of the items on my “Wish List” in ST executive editor Jim Bequette’s annual Christmas column. Bequette went on to say in the December ‘95 issue, “Layne assures me that he will be hunting big game next fall with that outfit.” By then I was convinced that the .30-378 Magnum would soon become a factory cartridge.

Then came my final push. In an article on rifles and ammo of the future (“Big-Game Rifles & Ammunition In The Year 2000”) in the December ‘95 issue, I wrote, “There was a time when the name Weatherby brought to mind the fastest cartridges of their breed, a reputation that eventually faded away as other companies introduced similar lines of cartridges. The domestication of the .30-378 and .338-378 wildcats and their availability in the fine Mark V rifle would once again put Weatherby up front in the velocity race. I believe it will eventually happen.”

These remarks obviously pushed Ed Weatherby over the brink. Whether or not his decision to introduce the .30-378 Weatherby chambering in a standard-production rifle was his way of getting me off his back, I really can’t say, but the important fact remains: It is now a reality.

Back in September 1995, Weatherby informed me that the chambering would be introduced at the SHOT Show in January 1996. Shortly after I received the good news, Ruddell asked me for load data and chamber dimensions; that information would be sent to Norma so the Swedish firm could begin development of factory ammo. The first Mark V rifle built in .30-378 Magnum went on display at the SHOT Show, and it is the one you see in this report. As I predicted in 1993, the rifle is called the Mark V Accumark.

NEW BREED OF WEATHERBY

A new Mark V variation, the Accumark is an extremely accurate long-range hunting rifle with an affordable price tag. It has a blued-steel receiver and a 26-inch stainless-steel barrel with lightening flutes. A combination of Kevlar and fiberglass, its synthetic stock has an aluminum bedding block shaped specifically for the Mark V receiver. The .30-378 Magnum I shot weighed 8 3/4 pounds. Mounting a Leupold 4.5-14X Vari-X III scope on the rifle with a Weatherby two-piece base increased its weight to 10 pounds, two ounces.

At present the Accumark is available in six Weatherby chamberings and two non-Weatherby rounds: .257 Magnum, .270 Magnum, 7mm Magnum, .300 Magnum, .30-378 Magnum, and .340 Magnum, as well as 7mm Remington Magnum and .300 Winchester Magnum. Rated weight for all calibers is the same, 8 1/2 pounds. The Accumark in .30-378 Magnum comes standard with Weatherby’s extremely efficient Accubrake muzzle brake, but it is an extra-cost option for the other calibers. This is why retail price of the rifle in .30-378 is $128 more.

Those who prefer rifles with plenty of firepower won’t get too excited about the Accumark in .30-378 Magnum. Its magazine capacity is two rounds, same as for other Mark V rifles in .378, .416, and .460 Weatherby Magnum calibers. On the other hand those who believe one good shot is worth far more than a pound of lead sprayed over the countryside won’t hesitate to hunt with a rifle that holds a total of three rounds. The Mark V magazine holds one more round of other Weatherby Magnum cartridges on the Holland & Holland-style case because they are smaller in diameter.

Weatherby factory ammunition is under development at Norma. The ammo and Accumark rifles in .30-378 Magnum are scheduled for delivery to Weatherby dealers in June ’96. The first cartridges to become available will be loaded with 180-grain spitzers, probably the Barnes X-Bullet, at a muzzle velocity of 3400 to 3500 fps. We should see a second factory loading with a 200-grain bullet rated at 3200 to 3300 fps. One thing is certain: The bullets in Weatherby’s factory loads will have to be of controlled-expansion construction in order to withstand the tremendous impact velocities of the .30-378 Magnum.

FAMILY TIES

The .30-378 Weatherby Magnum is a new chambering as factory rifles go but it has been around for over three decades. During the 1960s, the U.S. Military contracted Roy Weatherby to see how fast a bullet could be pushed from a shoulder-fired rifle.

Roy simply necked down his .378 Magnum case to .30 caliber, seated special 30-grain bullets made by Vernon Speer atop heavy charges of powder, and exceeded 5000 fps. Some time later other wildcatters used an experimental powder to exceed 6000 fps with the same cartridge.

The .30-378 Magnum is the fourth member of its family to be introduced by Weatherby. Its parent, the .378 Weatherby Magnum, was introduced back in 1953. It is basically a belted version of the .416 Rigby case necked down for .375 inch bullets and wearing the familiar Weatherby double-radius shoulder. In 1958, Roy Weatherby necked the .378 case up for .458-inch bullets and called it the .460 Magnum. The third cartridge came along in 1989 when Ed Weatherby created the .416 Weatherby Magnum by necking down the .460 Magnum case.

As a rule I find the .30-378 Weatherby Magnum to hold a slightly bigger velocity edge over its smaller cousin, the .300 Weatherby Magnum, once bullet weight reaches and exceeds 180 grains. When both are loaded to maximum chamber pressures and fired in 26-inch barrels, the .300 Weatherby will push a 150-grain bullet along at 3500 fps, which is only 200 fps or so slower than is possible with the .30-378 Magnum. But the bigger cartridge really starts to show a substantial advantage with heavier bullets and has a 250 to 300 fps velocity edge when loaded with bullets weighing 180 grains and heavier.

STOKING THE FIRE

Handloading the .30-378 Magnum is no different than for any other cartridge. It uses the same shellholder as its .378, .416, and .460 Magnum littermates, and reloading dies are available from RCBS and Redding. Unprimed .30-378 cases are available from Weatherby, or they can be formed from .378 Magnum brass. In the RCBS form set, die No. 1 pushes the shoulder back slightly and reduces neck diameter to .33 caliber. Die No. 2 squeezes the neck on down to .30 caliber. After a trip through the full-length resizer die, a case is ready to be loaded with a bullet and reduced powder charge and fireformed in the chamber of the rifle. The fireform load I used in the Accumark consisted of the 180-grain Speer and Nosler bullets seated atop 114.0 grains of H50BMG. Forming cases is a good deal for someone who already has a supply of .378 Magnum brass on hand, but since the process requires a couple of forming dies, simply using Weatherby factory .30-378 cases is less expensive.

Load data for the new Weatherby cartridge is a bit scarce as I write this, but the situation will improve as time goes on. The fourth edition of Nosler’s reloading manual will contain .30-378 Magnum data. It is scheduled for availability during 1996. Other components manufacturers will surely follow suit when updating their data manuals.

Heavy charges of slow-burning powders used in the new Weatherby cartridge call for a Magnum primer, especially when the ammo is subjected to extremely low temperatures during a hunt. Norma will use the Federal 215 primer in .30-378 Magnum factory ammo, same as it does when loading other Weatherby cartridges. I used that primer when working up loads for the Accumark, but the Winchester WLRM works just as well. I’ve not tried the CCI 250 or Remington 9 1/2M primers in this cartridge, but I see no reason why they would not get the job done.

As powders go, most of those commonly used for handloading other magnum cartridges are a bit too quick in burn rate, especially when 180-grain and heavier bullets are used. Even slow burners such as H4831, IMR-7828, RL 22, and N-MRP are a bit too fast for use with the heavier bullets. Among older propellants, Hodgdon H5010, which was originally developed for the .50-caliber BMG (Browning Machine Gun) cartridge, is ideal in burn rate for the .30-378 Magnum. Hodgdon’s H870 and AA 8700 from Accurate Arms are also quite suitable. Those two propellants meter through a powder measure more smoothly than H5010, but the fouling residue they leave behind is a bit more difficult to remove from the barrel.

H5010 (which is also one of my favorite choices for the 7mm STW) is a military surplus powder, and Hodgdon officials tell me their supply is dwindling fast. In fact, Hodgdon has already replaced it with H50BMG, a newly manufactured propellant with a similar burn rate. It is so new that labels had not been printed for its cannisters when I received my samples. I really like this powder in the .30-378 Magnum. It burns cleanly, produces maximum velocity, and accuracy is excellent when it is teamed up with the right bullet. In other words it is every bit as good as H5010 and readily available to boot.

As this article was going to press, I discovered that VihtaVuori introduced two new propellants, VV20N29 and VV24N41, which the company recommends for the .50 BMG. Their slow burn rates make them suitable for .30-378 as well. I’ll be reporting on the performance of these new powders in future ST articles. According to an engineer who works at the Norma plant in Sweden, his company will eventually offer a powder for the .30-378, but it is not known when it will be introduced or what its designation will be. Since Norma is loading .30-378 factory ammo for Weatherby, and since a powder developed for the Weatherby cartridge would work equally well in the .50 BMG (which is presently enjoying considerable popularity in long-range competitive shooting), it makes sense that Norma will eventually offer it to the cannister trade.

Other powder companies may also hop aboard this particular bandwagon. Both IMR and Winchester/Olin have long produced .50 BMG powders for the U.S. Military and those same powders would be equally suitable for the .30-378 Magnum. Whether or not they will be made available to handloaders is a question yet to be answered.

Winchester/Olin, IMR, and Norma, may or may not make their super-slow powders available to handloaders, but when all bets are placed, my money will be on Alliant as the next company to answer this particular need. I say this because that company has developed a new powder for the .50 BMG cartridge, and I’m sure it will work equally well in the .30-378 Magnum. The new propellant does not yet have an official designation, but if Alliant does decide to make it available to handloaders, it will probably be called Reloder 50.

THE PAYLOAD

In the bullet department, almost anything presently available will work fine for punching holes in paper targets with the .30-378 Magnum. Some of the most accurate long-range target loads I have developed through the years utilized the Nosler 180-grain Ballistic Tip and Sierra MatchKing bullets weighing 180, 190, 200, and 220 grains. I have also used the 240- and 250-grain MatchKings and found both quite accurate in a Jarrett heavy-barrel target rifle, but their extreme lengths require the use of a barrel with a rifling twist rate no slower than 1:9 inches. The 250-grain MatchKing has been discontinued, but its 240-grain mate is still available.

Due to the extremely high impact velocity possible with the .30-378, I consider a 180-grain premium-grade bullet of controlled expansion design the absolute minimum that should be used on larger game animals such as elk, moose, and the big bears. Of those presently available in that weight, I would choose Winchester’s Fail Safe, Nosler’s Partition, and Barnes’ X-Bullet. As heavier big-game bullets go, the Nosler 200-grain Partition would be my first choice.

Before leaving the subject of handloading, I must caution that the barrels of Weatherby rifles in most calibers have extremely long chamber throats. This freeboring, as it is called, allows the use of powder charges that often exceed the maximum one should use in a rifle of the same caliber but with a more standard chamber throat length. The Accumark in .30-378 Magnum is no exception. In order to reach maximum speed with that rifle, I had to use charges of various powders that were several grains heavier than are maximum in my Jarrett rifle with its shorter chamber throat.

The perception of recoil differs considerably among shooters, and while some may consider the Accumark in .30-378 uncomfortable to shoot, I find it to be less punishing than Weatherby’s .378, .416, and .460 Magnums. During my range sessions, I alternated between the Accumark in .30-378 and a Mark V without a muzzle brake in .300 Weatherby Magnum and found the .30-378 with its extremely efficient Accubrake more comfortable to shoot. I also tried the Accumark without its muzzle brake and recoil with full-power ammo loaded with 180-grain bullets seemed about the same as I feel when shooting a nine-pound rifle in .340 Weatherby Magnum without a brake.

I’m sure no small number of deer-size game will be harvested with the Weatherby Accumark and other rifles in .30-378 Magnum simply because it is such a great long-range cartridge. But it is really seen at its best when used for open-country hunting of elk, moose, and the larger African antelope. If there exists a better cartridge for sitting on one side of a wide canyon and dropping a big bull elk on the other side, I have not discovered it.

NOTE: All load data should be used with caution. Always start with reduced loads first and make sure they are safe in each of your guns before proceeding to the high test loads listed. Since Shooting Times has no control over your choice of components, guns, or actual loadings, neither Shooting Times nor the various firearms and components manufacturers assume any responsibility for the use of this data.


Specifications
Weatherby Mark V Accumark .30-378 Weatherby Magnum Bolt-Action Rifle

Distributor: Weatherby Inc., 3100 El Camino Real, Atascadero, CA 93422
Model: Mark V Accumark
Type: Bolt Action
Caliber: .30-378 Weatherby Magnum
Barrel length: 26 inches
Overall length: 46.25 inches
Nominal weight: 8.75 pounds
Magazine capacity: 2 rounds*
Safety: Two-position on bolt shroud
Stock: Synthetic with aluminum bedding block
Finish, action: Matte blued steel
Finish, barrel: Matte stainless steel
Options: Accubrake muzzle brake**
Calibers available: .257, .270, 7mm, .300, .340 Weatherby Magnums; 7mm Remington and .300 Winchester Magnums

Price: $1200 (.30-378 Magnum), $1199 (other calibers)

* Three rounds in other available calibers
** Standard on Accumark in .30-378 Magnum; $128 extra-cost option for other calibers



Weatherby .30-378 Performance Results

WARNING: Since the Weatherby rifle has a freebored chamber, maximum powder charges shown for it may be several grains heavier than would be considered maximum for a rifle with a standard chamber throat length. Reduce all powder charges shown in this chart by 8.0 grains for starting loads in other Weatherby factory rifles and by 12.0 grains for starting loads in rifles without freebored chambers.

NOTES: Accuracy shown for each load represents the average of three or more five-shot groups fired at 100 yards from a benchrest. Velocity for each load is the average of 15 rounds clocked 12 feet from the muzzle. Weatherby cases and Federal 215 primers were used in all handloads. Overall cartridge length was 3.645 inches with the Winchester 180-grain Fail Safe and 3.735 inches with all other bullets.


.30-378 Weatherby Magnum Accuracy

Roy Weatherby never got around to offering the .30-378 Magnum in his Mark V rifle, and if not for long-range riflemen of the northeast who shoot in 1000-yard competitions, the cartridge might have completely faded away. The .30-378 is tough to beat in long-range benchrest competition because it shoots flatter and bucks wind better than smaller cartridges. On top of that, its accuracy in top-quality rifles is legendary.

For a number of years, Earl Chronister held the world’s record for the smallest 10-shot group fired in 1000-yard competition, and he did it with a rifle in .30-378 Magnum. Chronister’s first nine 250-grain MatchKing bullets landed in a 3.125-inch group and even though wind pushed his 10th shot a bit astray, the group still measured an incredible 4.375 inches.

No doubt, hunters who go afield with their Mark V Accumarks in .30-378 Magnum will have accuracy stories to tell around the campfire. As you can see in my performance chart, the new Weatherby I shot carved out groups smaller than an inch at 100 yards with several loads, and I’m convinced it would have shot even more accurately had I given more time to developing loads specifically for it.

To see how accurate the rifle would be at longer range with an extremely hot barrel, I squeezed off several 10-shot groups at 300-yard targets using a handload consisting of Nolser’s 180-grain Ballistic Tip seated atop 122.0 grains of Hodgdon’s new H50BMG. The smallest string measured 2.80 inches, and that’s plenty accurate for my money!