Why .300 Weatherby ?


Well-Known Member
Mar 9, 2009
I have a question for all of you folks. There seems to be a quite a few of well respected individuals in the shooting industry that have chosen the .300 Weatherby as their general cartridge of choice. Why have they chosen this particular cartridge, other than for its' velocity ? Is there something that is inherent to this casing/cartridge that makes it the stellar choice? I am asking this to help me understand so I appreciate your honest , informational replys. Thank you for your information. Darrel
I used to own a 300 wby (I HATE thieves) and will own another one eventually. The 300 weatherby is an wonderful round that I truly came to love. The good parts about it are the brass quality, bullet selection, and tendency to have a bit of free bore. Weatherby brass is of excellent quality and consistency. You have an excellent bullet selection and can load any of the 30 caliber bullets while still obtaining good to excellent muzzle velocities. The free bore can be both a blessing and curse but in general terms I lets you seat your bullets out a little farther thus giving you a little more room in the case.

Now on the other side of this you sill have the belt and the double radius neck. Both of which a good many people don't like. The belted mags catch a lot of flak about the belt on the case and the infamous bulge associated with it. The truth is that with a little education and some equipment you can get around the whole issue. Then there is the trademark of weatherby rounds the double radius neck. Some don't like it and think it's silly. I myself like uniqueness and was found of it. However the neck design really doesn't serve any practical purpose I know about. To my knowledge Roy was sort of like me and he used that design to be different. But I could be wrong about this. I have seen a few unconfirmed sources mention that the neck design is more efficient however that contrary to common knowledge on case design.
here is one to add.mine is a ackley imp. 300 weatherby.or some may say 300H-H.for me its a good case and by going with the ackley it gives me a little more powder room.and to add the first gent said it all.just go ahead and get you one. but for me I would make it a bull barrel or at least a varment weight.and if you don't have 300 weatherby brass and can get your hands on some 300H-H just blow them up to a 300 weatherby.just like I said get one and I'lll sale ya some 300H-H brass at a good price.that way you want have to get that high dollar brass to start with.LOL
cause......... "Nothing shoots flatter, hits harder or is more accurate."

On the shoulder thing. I mess around with air flow with race car cylinder heads and I have over the years come to the opinion that, how ever slight, the double radius shoulder flows the gasses a bit more efficiently than all the sharp edge shoulder rigs do. You won't find many rocket engines that have sharp edged nozzles either. Roy Weatherby's design was devinely inspired and is still very current for modern man. Just my opinion though. FWIW

Back to the facts:

And besides, a bullet out of a Weatherby just kills better.

It's all the 300 mag I will ever need.
I am also a big fan of the 300 Wby. Mine is a custom rifle I built several years ago; but it is the most accurate hunting weight rifle I have ever seen. This summer I took it to my range in Idaho and shot (over an open hay field with no wind flags) 2, 3 shot groups at 600, 1000 and 1212 yards. The groups measured 1.5 and 3.5 inches at 600, a little over 3 and 5 inches at 1000 and 1212 yards both. I also shot 1, 13 inch group at 1212 when I did not hold the rifle tight enough. 210 Bergers at 2980-3000 fps depending on the weather.

I also think the double raduis shoulder has more advantages than disadvantages.

Until the 300 RUM matches the success of the 300 WBY at 1000 yard matches the 300 Wby is the best 300 caliber magnum ever mas produced, and maybe the best ever period.
For those of you who have experience with the 300 Wthby, how does it stack up against the 300 WM? I've always heard over the years that factory ammo is quite a bit faster, but looking through most reloading manuals the difference is minimal at best.

Looking through Noslers latest manual the hottest 300 WM load for a 180 is 3160 fps out of a 24" bbl. The Wthby shows 3198 fps out of a 26" bbl.

The 300 Wm load for a 200 gr is max at 2972 while the Wthby is 3039. Have any of you loaded for both calibers with similiar barrel lengths? If so, what are your findings regarding velocity and accuracy? Just curious.
You really should not rely on hand loading manuals for a definitive answer on a lot of things, maximum velocity is one of them. A difference in barrel makers, throat, free-bore, etc can easily effect the velocity 100+ fps. All that being said the 300 Wby has a lot more case capacity than a 300 Wm and should be good for at least 100-150 fps more on an average basis. The Wm is a very fine cartridge though, just not as fast as a 300 Wby.
Not really relying on it as definitive, which is why I asked you guys the question. Just looking for some first hand knowledge comparing both calibers. I am getting close to rebarreling a 300 WM, the barrel just showed up a few weeks ago. I am pretty set on staying with that caliber but I am also somewhat entrigued by the Weatherby. I just don't know much about this caliber, only limited information that I have read here and elsewhere.
I owned a Weatherby Lazermark some years back, and with handloads, was getting 3250fps with 180gr bullets. This was in a 26" barrel. My current .300 Wby is a Winchester M70 and haven't checked my loads over the chronograph yet. It also has a 26" barrel.
In my 26" Accumark real world specs are:

180 grain Partitions go 3300fps with a trace of extractor mark in hot weather. Though an extremely successful Elk load I abandoned it in favor of the balistically supiorior 200 grain Accubond.

200 grain Accubonds go 3100fps. No extractor mark of any kind. I had it up to 3200 but this powder is temp sensitive and when shot in warm weather it showed too much of an extractor mark. 3100fps is a very happy load.

Since the 200 grain Accubonds have worked so well and have shown me a 3 shot group of 3" at 885 yards and consistantly 1/2 MOA or less at all tested ranges and blown everything I have shot at off its feet I have decided to abandon this bullet in favor of the 210 Berger. Testing begins next week for these.

These speeds are attainable using real Weatherby brass, CCI-250 or Fed 215 primers and IMR 7828. Case life is indefinite so far. I quit counting at 20 times.

Every 26" Mark 5 has been able to match these specs that we have tried. I had a 24" Mark 5 Deluxe that was MagnaPorted and it showed pressure at 3050 with 180's and it took 4 more grains of 7828 to do that. I sold that one.

Darrel Holland once told me that with a 30" barrel the 300 Wby will do anything the 30-378 will do with a 26" barrel.

If I could ever wear out my Accumark barrel I intend to see if he is right.
In my 26" Accumark real world specs are:

Since the 200 grain Accubonds have worked so well and have shown me a 3 shot group of 3" at 885 yards and consistantly 1/2 MOA or less at all tested ranges and blown everything I have shot at off its feet I have decided to abandon this bullet in favor of the 210 Berger. Testing begins next week for these.

That's the nature of the beast isn't it. It's too easy to get bored or just the urge to try something new. Hey, thanks for sharing this info. It's pretty much what I expected, just wanted to hear some straight info on this.
I have had quite a bit of experience with the 300 wby over the past 35 years. I got my first 300 win mag in 1971. The 300 wby is a superior cartridge to the win mag in all respects. It is probably the best all around big game cartridge of the last 50 years. With the inherent accuracy and tremendous killing power only recently has it been challenged by the new high performance 300 magnums like the ultramag, lazzeroni and 30-378, etc. Many still say the 300 wby is still the best choice because it is still right there with velocity while retaining exceptional accuracy and much better barrel life than the larger big 30's. I have at least five 300 wby's right now but sold my 300 win mags through the years because they just didn't measure up to the 300 weatherby. Even now, fifty years later, it is still as good as anything out there when all facts are considered. Legendary cartridges are that because they stand the test of time and remain as good as it gets. The 300 weatherby is a legendary cartridge.

Do not compare any weatherby mags to other cartridges in loading manuals. The loads are typicaly very watered down for the wby's because of many custom barrels not having freebore. For liabilty reasons published loads are typicaly light. Where this is most noticable in comparisons is with the 7mm wby vs 7mm rem and 300 win mag vs 300 wby. Both wby's will considerably outshoot the 7mm rem and the 300 win but you will only learn this by owning and loading/shooting all of them regularly.

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