A Medium Bore Rifle for
Alaskan Barren Ground Caribou


The Culmination of a Long Morning of Stalking

An Adventure Hunt

In March of 1999 my brother Steve called me and, after deprecating roundly upon our lack of initiative in fulfilling our mutual desire to go on an "adventure hunt", challenged me to go to Alaska to hunt caribou. It took me little time to acquiesce. Alaska is today still, particularly for the American hunter, what Africa was to the late 19th and early 20th century British hunter of big game: an unspoiled wilderness, a "colonial" heritage, untamed, savage and dangerous; a magnificent country inspiring of all that burns most brightly in the spirit of sporting adventurers.

This was to be an unguided hunt, coordinated by Cabela’s Outdoor Adventures (insuring the reputability of the outfitter) and outfitted by Lake Clark Air (an arrangement that I highly endorse for those who are physically prepared for the environment and the rigors involved). Two hunters are flown to a drop camp in the remote wilderness and retrieved seven days later. The outfitter provides all basic camping provisions and equipment, the hunters bring their personal gear and weapons. It sounded ideal. My brother and I have never been too keen on having a guide go around holding our hand anyhow. We grew up hunting whitetails in both bottomlands and beanfields, absorbed Selous’ Recent Hunting Trips in British North America and Whelen’s Wilderness Hunting and Wildcraft, and were eager for the challenge.


The Problem of the Rifle

The question of what rifle to bring was foremost among our considerations. Barren ground caribou are large animals, bulls averaging between 300 and 400 lbs. Though they are reputed to be not very tough to put down, they are often shot at respectable distances (exceeding 200 yds) in wide open country graced with blustery conditions. Most authorities recommend something on the order of a .270 Winchester, .280 Remington or .30-`06 Springfield. For my brother the choice was relatively simple: his Ruger M77 MkII in .270 Winchester caliber with its 3-9X Zeiss scope fit the bill perfectly. One day of 150 grain factory load sampling at the range produced a classic cloverleaf pattern at 100 yds with Nosler Partition bullets. He bought several boxes of the same production lot.

My rifle, however, posed more difficulties. My whitetail rifle at that time was a sweetheart, a Remington Model 7 in 7mm-08 Remington caliber, the perfect Southern whitetail rifle in my estimation, but lacking in velocity for really long range shooting with 160 gr bullets. Actually, it would be fine. Goodness knows countless caribou have been slain with such weapons. But I had a project in mind that was ideally suited for hunting heavy animals at long range. I was also interested in having something capable of stopping a brown bear at spitting distance.

Some years before I had made a first effort at my heavy game / plains game rifle. I had settled on the .340 Weatherby cartridge as my optimum choice for this application for several reasons. Why the .340 Weatherby Magnum instead of the .338 Winchester Magnum? Well, why not? My action of choice was the Remington M700, so the cartridge length was no issue. Moreover, it offered more flexibility in handloading than the shorter domestic brand, plus with .300 Weatherby Magnum cases being produced by Remington and available in bulk through Midway, by a simple pass through the sizing die I would have an ample supply of inexpensive cases. The real reasons, though, centered on the cartridge’s extreme flexibility. Bullets for the .338 caliber are produced by every major and custom manufacturer of interest in weights and styles ranging from 160 grain X-Bullets to 300 grain Woodleigh solids. Not even the popular .308 caliber offers a broader range of options. Moreover the .340 Weatherby combines the flat trajectory of the 7 mm magnums with the big bore authority of the .375 Holland & Holland Magnum. Granted, it’s a lot of gun, but for long range work against big game or dispatch of really large game animals like elk or moose or bear, its near perfect.

My problem was that my first .340 Weatherby rifle was simply a rechambered, factory stocked Model 700 BDL originally chambered in .338 Winchester Magnum. Unfortunately, it never shot well; whether due to a botched rechambering or just because it had a lousy barrel or poor bedding, or all three, I’ll never know. But I know my own abilities well enough to know that it wasn’t just me, recoil notwithstanding. The best group I ever saw with that rifle was more than 2 inches at 100 yds; most hovered around 4 to 6 inches. It was truly wretched.

I had been considering my options for doing the job properly when my brother forced me to the conclusion that I had to either buy a new rifle or else fix the .340 Weatherby. This was now April and the hunt would take place in October, leaving little time for a custom rebarreling. After much scouting around, I entrusted my dilemma with gunsmith Fred Zeglin. His line of proprietary cartridges had been documented recently in several publications and he makes custom rifles and precision handloading dies. I found Fred to be an interesting conversationalist in technical matters and very helpful in finding a solution. Although I had considered a Lilja or Shilen barrel, time considerations argued against a true custom shop barrel. Fred persuaded me to use a Douglas XX premium grade chrome-moly barrel, with which he had experienced much success in the past. I also wanted it Magna-Ported and cryogenically stress relieved. These were the things that created the schedule risks, since the barrel had to be sent out for this work.

I specified a 25 inch medium-heavy sporter contour with slightly more weight than my original barrel to help moderate recoil, but nothing as muzzle heavy and clumsy as the style of "sendero" or "tactical" rifles that many hunters are switching to; he recommended a No. 5A contour. Barrel mass doesn’t guarantee accuracy and all barrels have natural harmonics. Cryogenic treatment would, I hoped, minimize the detrimental aspects of the barrel’s harmonics. The main objective was for a barrel that would shoot the same hot or cold. My original rifle had positively vicious recoil and uncontrollable muzzle whip, worse by far than my Brno ZKK 602 in .458 Winchester Magnum with the hottest 500 grain loads you please. But it was Magna-Ported, so I thought I would give that a try on the medium bore. I have no use for muzzle brakes. In the interests of time I opted for an H-S Precision synthetic stock (model PSS55 with a heavy "African" barrel channel), as the factory stock was suspect (i.e., the bedding). I also asked for a standard throat rather than the Weatherby "freebore". Most importantly, the action was to be trued and carefully fitted.

I gave Fred until the first of September to pull off this miraculous transformation of a useless noisemaker into a long range hammer and the rifle was completed a week early. It was gorgeous. A new satin blue finish covered the metal and the H-S Precision stock had a very handsome brown with black web textured finish that gave it a warmer, more traditional feel than most synthetic-stocked rifles have. I had intended to have an English walnut custom stock made for this rifle with traditional appointments, but having now held that stock I know that it will never be replaced [Or at least not for nearly a decade; see Part II]. It fits perfectly, with a long wrist and slender rounded forearm. All of this was accomplished for slightly over $1000, which my friends is a true bargain these days, especially considering what $ 500 or even $ 600 won’t buy you from a major manufacturer any more.


.340 Weatherby Magnum Remington M700 BDL with Douglas XX Premium Barrel and H-S Precision Stock


Load Development and Range Work

The true test is in the shooting though and after reattaching my Leupold Vari-X II 4-12X, I started it immediately. I didn’t have time to properly break in the barrel before I started load development, but I was careful to thoroughly clean the bore of copper fouling after every 15 to 20 shots. The best thing for this purpose which I have used is Birchwood Casey Super Strength Bore Scrubber. It is ammonia based and will take your head off if you smell it, but it works really well. Slow, gentle brushing with a bronze (not stainless steel!) brush is also effective.

I started with two potential bullets in mind: the Nosler 200 gr. Ballistic Tip (because of its reputation for accuracy and suitability) and the 210 gr. Partition (which I preferred). Other good options are available, but I had to narrow the variables. I tried three powders after carefully considering several different manuals: IMR-4350, Vihta-Vuori N160 and Hercules (now Alliant) Reloder-22. I have reached the older and wiser stage in handloading wherein accuracy, not velocity, is all important. It is an obsession, second only to safety and reliability. As Townsend Whelen said so well: "Only accurate rifles are interesting". Someone has suggested that this is now cliched, but the current obsession with hypervelocity compels me to reiterate it.

Despite indications of maximum velocity potential in the manuals, accuracy results with the IMR-4350 were not as promising as I hoped. In truth the barrel was probably just too rough, those same loads would probably shoot better now. But the other problem was that the most accurate load was second to the mildest, negating any advantage favoring the faster powder. Its also likely that my shooting was a bit rusty. I highly recommend four shot strings when conducting accuracy testing, even for heavy recoiling rifles, unless you have the composure of a Zen master.

Vihta-Vuori powders were introduced in this country a few years ago amid claims of phenomenal accuracy, so I wanted to try N160. Unfortunately I had no data for the 340 Wby Mag. This powder is virtually identical in burn characteristics to Reloder-19, producing approximately 60 fps less velocity with equal charges, so I used data for the Hercules-Alliant powder as the basis for my load development with the N160. It immediately produced marked improvement in accuracy, with sub-MOA groups appearing at once with the Ballistic Tip and a velocity of a little over 3000 fps; well short of the maximum possible but quite respectable.


Range Testing the Loads at 100 yds

I really preferred to use the Partition bullet however, considering its (admittedly unlikely) secondary role as a bear slayer. The Partition (I thought then) would penetrate about 25 % deeper. The same load (84.0 gr.) behind this 210 gr. bullet achieved about 2940 fps and seemed to suggest (with my 3 shot string) a rather fantastic accuracy below the 1/2 MOA level. I was excited now. This rifle could really shoot!

Still I knew that the cartridge was capable of more performance than that if only the rifle would favor a load in the higher velocity ranges. I had enjoyed good load success in the past (all things considered) with the very slow powders like Reloder-22 and IMR-7828. Notwithstanding most manuals’ unwillingness to even try such powders with lighter weight bullets I ventured, before giving up, to at least try Reloder-22. I’m glad that I did. Not only were the loads milder in terms of pressure at any given velocity but I found a real "hummer" (I never did reach a maximum load in my series - Alliant shows a max load of 89.2 grains of RL-22 for the 210 gr Nosler Partition).

Most groups hovered between 1 to 1.5 inches, but with a load of 88.0 grains after three shots I could only see one mark on the paper near my aim point. Granted it was getting twilight and my eyes were growing tired, but no other hole was visible for several inches in all directions. "Couldn’t be", I thought. "Or could it?" I was shaking with excitement when I got to the target.


A "Zen Moment": Three Shots in 0.24 inches at 100 yds

It was true. A single ragged hole for three shots at 100 yards, measuring just 6 mm, center-to-center (I think I can honestly call the far right hole a "flyer"). That’s 1/4 MOA. My best group heretofore was a five-shot effort at an honest 200 yards that you could cover with a quarter, using a Ruger M77 in .270 Winchester. That was a fabulous rifle, but I’ve no doubt that this .340 Weatherby could whip it. [Over the years this rifle has maintained a phenomenal level of consistent accuracy] The cherry on top was the 3050 fps velocity, at least 100 fps more than the most accurate load with N160.


Table of Load Development Data

Bullet Type / Weight
Powder Brand / Type
Powder Weight
Pressure
Velocity
Accuracy Remarks
200 gr Speer Spitzer Hodgdon H-4831
84.0 gr
Mild
2975 fps
2.0 in

Vihta-Vuori N160
85.0 gr
Mild
2950 fps
0.9 in
200 gr Nosler Ballistic Tip Vihta-Vuori N160
84.0 gr
Mild
2940 fps
0.4 in

Vihta-Vuori N160
86.0 gr
Warm
3100 fps
1.2 in
210 gr. Nosler Partition Dupont IMR-4350
80.5 gr
Mild
2975 fps
1.7 in (2 in 0.4 in)

Dupont IMR-4350
83.5 gr
Warm
3075 fps
2.3 in (2 in 0.6 in)

Vihta-Vuori N160
84.0 gr
Mild
2940 fps
1.5 in (2 in 0.2 in)

Vihta-Vuori N160
86.0 gr
Warm
3020 fps
1.0 in

Hercules RL-22
85.0 gr
Mild
2930 fps
0.9 in

Hercules RL-22
88.0 gr
Moderate
3050 fps
0.2 in

Notes:

1 -- All loads used Federal 215 magnum large rifle primers

2 -- Velocities are estimates based on published data

Warning: Use this load data at your own risk. No liability is assumed for the use of this data in any other firearm. It appeared to be safe in the test rifle, but was not subjected to pressure testing. Exercise safe reloading practices. Starting loads should always be reduced by 10% from the maximum load.


Notes on Handloading

Careful load development pays off. One grain of powder more or less and the groups opened up to 1 MOA. Harmonics are real. Use them. Throwing powder charges of these size is never accurate to more than plus or minus 3 to 5 tenths of a grain. For an investment of 30 seconds more per round with a powder trickler you can have loads that are equal to the precision and accuracy of your scale. Not to do so is to squander accuracy.

I have a few remarks about handloading and pressure testing in particular. Handloading is a dark art, not a science. I use an expensive Mitutoyo micrometer to measure case expansion, but it gives an indication of a trend, nothing like an absolute measure. A perfect example of its unreliability in the best of hands is demonstrated by the Speer Reloading Manual Numbers 12 and 13. The loads for the .300 Weatherby Magnum in No. 12 were created using case expansion rules rather than direct pressure measurement and recommend a maximum charge of IMR-7828 over a 180 grain bullet that is 5 grains heavier than those developed with an instrumented pressure barrel! The best gauge of pressure safety is common sense. There are far too many variables involved in handloading for any loading data to be more than a guide. But if you consistently "push the envelope" you will rupture a case head or blow up a gun, I promise you.

Brass comes in many hardnesses and it work hardens. Virgin brass will expand far more at the same pressure than once or twice fired cases. Expansion testing must be conducted with cases which are in identical condition: all from the same lot, with identical loads fired in them for the same number of times. Even so, no valid comparison may be made between these tests and tests performed with the same cases previously. Virgin cases are more forgiving than work hardened cases; they will flow rather than burst. The case is a gasket. Look for indications that it will yield and rupture, then back off from that load if you see them. Indications of danger are bright, scraped extractor marks, sticky extraction and highly cratered primers. This is not a maximum load, it is over maximum. But be aware that with hard cases you will see fewer indications and will achieve higher pressures before any appear. On the other hand, virgin cases will expand significantly after one firing (resulting in larger case capacity) and any load development will probably have to be adjusted. I suggest using once-fired cases.


Measuring Case Expansion with a Digital Micrometer

Some will contend that I am profoundly overgunned for caribou, but this rifle shoots like a dream now. The Magna-Port has reduced recoil to the point that it is no more of a consideration than that of a standard deer caliber and muzzle whip is non-existent. Consequently, I have a rifle with a delivery far superior to many smallbores, extremely flat trajectory, and one very pleasant to shoot. And should I need to call on it for more, it throws more lead than a 7 mm. I intend to go on safari in Africa someday and this rifle will be my first choice in that endeavor as well (It was; see that story here: A First Safari in Namibia). Should I ever shoot whitetails off a soybean field again I’ve no doubt but that it will be what I depend upon (maybe with the 200 gr Ballistic Tip or a 175 gr. X-Bullet).


The Hunt

The moment of truth came on a blustery, overcast October day in the face of a steady cold drizzle, near the junction of the Mulchatna and Nushagak rivers, when she had her baptism of fire. I had already lost opportunities against two or three excellent trophy bulls, including one with massive beams which taunted me whenever I got into stable firing position since I could then see nothing but antlers over the rise! These animals are wary and will cover ground very quickly. Good fortune brought a huge herd of perhaps 300 caribou to a small pond permitting me to stalk within 250 to 600 yards of them without disclosing my presence. I was on flat, nearly featureless ground and could not easily approach closer, nor could I find a high spot to shoot long distances, but about three good bulls were within 300 yards of me, so I propped my rifle on my rucksack and drew down on my pick. My rifle was sighted 2.5 inches high at 100 yards, so at this distance (about 275 yards) I was in the "point blank" range. I aimed on the front of his chest to account for his walk. The first shot hit him hard, low in the chest angling forward across the heart region. He staggered slowly forward. I calmly shucked a new round and put one carefully through his shoulder. He fell instantly to the hit. Either would have been sufficient, but I wanted to be sure. I saw his antlers shake once and his breath come in great gray wisps for a few moments, then no more.

On approaching the fallen bull, I realized my worst apprehension: two caribou lay dead. A small cow some distance behind the bull that I could not see had been struck in the brain by a tiny fragment of the exiting Partition and instantly slain. The fragment was the separated and ablated base of the forward core and weighed just 31.4 grains. Let that be a lesson in lethality. It would have been just as lethal had it entered the chest cavity, but she would probably have wandered off before collapsing. Caribou are frequently clustered together and although I had made a concerted effort to have clear path behind my target, I still made a mistake. Fortunately, a forgivable one.


Forward Core Remnant of 210 gr Nosler Partition Recovered from Cow Caribou (31.4 grs)

My brother dropped a superb bull at an honest 400 to 425 yards (I verified this based on my scope reticle measurement, his holdover, and the trajectory as computed and adjusted for local weather conditions). The .270 Winchester and Nosler Partition lived up to their respective reputations, delivering a lethal blow on the first round. The big bull remained on his feet, but staggered down the hillside. Steve continued to shoot until it fell, but I was watching through the spotting scope and knew that the bull was dead on his feet from the first shot. The bull was hit twice in the heart area and once grazing the spine. Steve remarked, "Jack O’Connor would be pleased". He would indeed. No hypervelocity, just good performance by both cartridge and shooter.


My Brother with His Outstanding Caribou Bull

Continue to Part II of A Medium Bore Rifle for Alaskan Caribou

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