Dec 26, 2007
An Excellent Big Game Cartridge

After hunting with a 340 Weatherby that belongs to a friend of mine and who was gracious enough to let me use it almost 20 years ago, on a mule deer hunt in Colorado, I was hooked. I always wanted one but got all tied up in other cartridges and rifles. That 340Wby really reached out and touched that buck at 476yds and put him down in a heart beat. It will be exciting to finally receive my Custom Mark V chambered in 340Wby sometime next week. I really like my smith's work but more importantly I trust his work. He has always put together real shooters for me. His work is straight-forward, uncluttered, looks good and is very clean, but most of all it is accurate. My custom has a #2, 26” Krieger Stainless barrel with a German Mark V receiver, bedded in a McMillian stock. This is a serious and significant big game rifle and cartridge. Anyone who has owned a Mark V rifle chambered in some of the other Weatherby cartridges is usually a fan of the 340Wby. It is a real magnum with enough recoil to prove that claim, but not enough to require a brake.

This is truly one of the best if not “THE” best cartridge Roy Weahterby ever produced. It is an exceptionally versatile all around cartridge for big game. It has reasonable recoil, with only the 250-300gr bullets being a little much for some people. Most of us who use the magnum cartridges when hunting big game will not have an issue with the recoil. The new cartridges like the 338 Federal, the 325WSM and the old classic 338Winchester Magnum are not able to run with it, nor can they use the heavier bullets as well or with as much punch.

The 338Rum is not really a significant improvement over the 340Wby. The 338Rum has 104.6grs case capacity while the 340Wby only has 93.5grs case capacity. Yet the 338Rum in muzzle velocity comparisons across the spectrum of 200gr, 210gr, 225gr and 250gr when using premium factory ammo contrasted with Weatherby factory ammo made by Norma for the 340Wby with same weight bullets - the 340Wby had a combined velocity of all four weights of over 300fps faster than the 338Rum that uses 10.5% more powder. To be fair Norma does load Weatherby ammo at greater pressures than the 338Rum ammo is loaded. The hand-loader with the 340Wby can get close and even sometimes at or just a little above Weatherby ammo. There are four reasons that I believe this is possible, and the reasons are with the right powder, the Mark V action, Freebore, Double Radius Shoulder and Norma brass. The 338Rum does seem to suffer a bit from diminishing returns. The 338Rum has a rebated rim and I am not crazy about that. It has it's fans and it is deadly on big game and when you hand load the 338Rum you can out run the 340Wby by a little bit.

The .340Wby and its case volume I believe are the limit that makes any sense for a bullet of the .338" diameter in a pure hunting rifle. I know there are those who really like the 338-378Wby but I do not like brakes on my hunting rifles and that eliminates the 338-378Wby as far as I am concerned. Without a brake it is not very pleasant to shoot and I am not recoil sensitive. The 340Wby is a perfect balance of velocity, powder charge, bullet weight, power and performance for a serious big game cartridge in .338” diameter.

This allows the 340Wby to be right in the middle of good company filling a true niche, making it a true all around big game cartridge. When you consider that it is chambered in the Mark V rifle and shoots flat (like some of the 300 magnums) and hits hard (like the some of the 375 magnums) there is no doubt about its pedigree.

The 340Wby is not a compromise by any stretch of the imagination. On the contrary, with the bullet and powder selections of today, the 340Wby is arguably the best all around big game cartridge ever conceived. It is surely one of the best elk and moose cartridges, with no problem anchoring the biggest bears in quick fashion. Interestingly enough, if your 340Wby can accurately handle lighter bullets, it can reach out hitting deer and hogs like Thor’s Hammer. Not destroying any more meat than the 7mm and 30 caliber magnum cartridges.

A hunter in the field with this one cartridge could take everything from deer to the largest Alaskan Brown bears and even put a Bison down in short order. With the 230-300 grain bullets it will buck the wind at distances that most hunters would consider reasonable and with plenty of energy to anchor anything in North America and most of Africa (where legal to use in Africa). Also, with some bullets and loads in the right hands and with good optics, it is a very effective round that can be used to take game at long ranges.

Since 1962 as a response to the 338 Winchester Magnum, the 340Wby has preformed without question. Easy to load for, accurate, reasonable recoil if stocked correctly and hits like a sledgehammer. With velocities that are perfect for premium big game bullets manufactured for the .338 caliber - the 340Wby can kill everything from “Mice to Tyrannosaurus Rex ” and I would add, even a big mean-spirited brown bear up close. This figurative language, sums up accurately the impressions and capabilities of the 340Wby.

Most in the hunting world know that the 30-06 with a 180gr bullet has been and is very affective in most situations and on most game given proper circumstances. Also the effectiveness of the 300Win Mag or the 300Wby using a 180gr bullet is unquestioned. In light of this fact a 340Wby using a 250gr bullet, has a striking energy that is 40% greater than a 30-06 that uses a 180gr bullet. Also, the cross-sectional area of the 250gr bullet allows it to hit like a freight train. The greater momentum factor of the 250gr bullet, allows for deeper penetration while releasing much more energy over a greater distance along the wound channel, due to 70grains more weight and higher velocities. The 340Wby is a 338Win Mag on steroids.

To put things in perspective, the 30-06 moving a 180gr bullet at 2800fps generates 3,122ft pounds of energy at muzzle with a 180gr bullet. The 340Wby using a 250gr bullet turns out 3,137ft pounds of energy at 400yds. Needless to say, the 340Wby is a highly effective big game cartridge with a lot of authority at its disposal with power to spare for up close and far off work when taking game.

It has tremendous potential as an all around big game cartridge for deer, along with the largest, toughest and heaviest game in North America. It is a tremendous medium bore with great legs and a big punch. It is a true sprinter like the 300mags and has a hard quick crushing blow like the 375mags. It is fast and hard-hitting. Bullet selection ranges from 180 grains to 300 grains to meet any need the North American hunter would engage. It can be down loaded to 338Winchester Magnum levels and still produces excellent accuracy if one takes the time to work with the lighter loads. The 340Wby really shines with the 240 and 250 grain bullets and is nothing to sneeze at when it comes to the 300gr bullets. The 240gr North Fork is my go to all around hunting bullet on big, heavy tough game as well as dangerous game up close or at medium ranges. The 250gr AccuBond, Partition and Sierra Game King bullets are my favorites for deer and elk at any distance I can shoot with good accuracy in the field.

On smaller species of big game one can use the 180gr to the 215gr bullets. Now there are two bullets in this weight class that stand out on the smaller species of big game - while being the exception in this group due to the fact that they are also highly effective on the larger species of big game. I am making reference to the 210grain Nosler Partition and the 210gr Swift Sirocco. The 210gr Partition and Sirocco’s can be pushed at velocities of between 3150fps and 3225fps with very good accuracy. They are flat shooting and hard hitting. The intermediate class for the 340Wby is the 225gr bullets. One of the bullets in this class stands alone on terminal results and that is the North Fork 225gr. It is a bullet that has tremendous terminal impact on game with great penetration and allows the 340Wby to stand out as an alternative to the heavier bullets on bigger animals, including dangerous game.

When hunting the really big stuff the 230gr, 240gr, 250gr and 300gr bullets due to their great shapes and construction are best. The 230gr – 300gr grain bullets do not have to apologize, nor are they inferior for any of the tasks handed them when taking big or dangerous game. I am now hand loading at the moment for the 340Wby using a friends rifle to get a leg up on experience loading the 340Wby before my Custom gets here.

The 340Wby can push:

1. The 200gr AccuBond at a Muzzle Velocity of 3225fps with a Muzzle Energy of 4620 ft. lbs.

2. The 200gr Hornady Spire Point at a Muzzle Velocity of 3221fps with a Muzzle Energy of 4607 ft. lbs.

3. The 225gr Barnes TSX and X and Hornady Spire Point at a Muzzle Velocity of 3001fps with a Muzzle Energy of 4499 ft. lbs.

4. The 250gr Nosler Partition at a Muzzle Velocity of 2941fps with a Muzzle Energy of 4801 ft. lbs.

a. The above is Weatherby ammo using Norma Powder.

5. The 240gr North Fork at a Muzzle Velocity of 3066fps with a Muzzle Energy of 5009 ft lbs.

6. The 250gr Nosler AccuBond at a Muzzle Velocity of 3032fps with a Muzzle Energy of 5103 ft. lbs.

7. The 250gr Nosler Partition and Seirra SBT at a Muzzle Velocity of 3041fps with a Muzzle Energy of 5133 ft. lbs.

a. The above are handloads using IMR7828 and RL-25

I have wanted a 340 Weatherby Magnum for some 20 years now and I am so impressed and awed by the cartridge since I have been working with load development for the 340Wby. At this time I am developing hunting loads for the fall hunting season of 2010. As a hunter, shooter and re-loader, discovering what others have known for years is a lot of fun.

The 340Wby is hard to beat as an all around big game cartridge. It is easy to load for, shoots flat, hits hard and according to a multitude of hunters and guides, brings home the bacon. It truly is and has been one of Roy’s classic cartridges and in my opinion it is his best. Yes, I even like it better than the 300Wby - which I have owned and hunted with off and on for the last 15 years. The 338Win Mag has been fun to hunt with and is a very effective cartridge on game, so I know the 340Wby from my hunt in Colorado years ago and what others have said, will be all the 338Win Mag is and much more. The 340Wby will for years to come, be used by the discerning and informed North American hunter and those who appreciate the outstanding qualities of the Mark V. After the 2010 and 2011 hunting season I will up date this article with the results.
Here is a picture of the mule deer I shot with my friends 340Wby back then. Had it mounted because at that time it was the longest shot I had taken on a deer.

Don't anyone think I am putting down the 338Rum in this article. My comparisons are only with factory made ammo not what can be done by reloading the 338Rum. When you reload the 338Rum you can out run the 340 a little. Thanks, did not want any miss understandings.
JD338":eojtt60n said:

Nice write up on the 340 Wby.


Thanks JD

JD, did you say that you have settled on the 250gr AccuBond for your 338Rum or did I get that wrong?
Correct, I have decided to just run with the 250 gr AB. The .575 BC offers great down range performance.
It will be a good choice in your 340 Wby. :wink:

JD338":g25zzruh said:
Correct, I have decided to just run with the 250 gr AB. The .575 BC offers great down range performance.
It will be a good choice in your 340 Wby. :wink:


If it shoots good (hunting accuracy) it will be what I will run with in the lower 48 because of the BC. I have settled on the 225gr AccuBond for my 358Win and that is the only load I use for it now when it comes to hunting. thanks Mike :)
You are going to have fun with the 340! I am having a blast with my 338 Win Mag and the 275gr Speers. I couldn't imagine what the 340 could do with those heavier bullets. I think the 338 bores really come alive with the 250 and heavier bullets. Hope your rifle is a tack driver. You 338RUM/340 Guys are giving me case envy! I may need to step up one of these years! Scotty
beretzs":1rpfosid said:
You are going to have fun with the 340! I am having a blast with my 338 Win Mag and the 275gr Speers. I couldn't imagine what the 340 could do with those heavier bullets. I think the 338 bores really come alive with the 250 and heavier bullets. Hope your rifle is a tack driver. You 338RUM/340 Guys are giving me case envy! I may need to step up one of these years! Scotty

You don't need to step up if own a 338Win Mag that shoots like yours does. Once again, that was a good 200yd target.
Thanks again. I do like my M70 alot, and figure the 338WM will handle about anything I will ever use it for. The 3000 with the 250 sounds pretty appealing though. I might have to mess with those one of these days. That is some super power. Scotty