I was doing some comparisons and it makes me think why the 338LM required so much research when the answer was already there, the .340 Weatherby Magnum.

200gr Nosler Partition

340WM 3290fps 4797ft/lbs
338LM-- 3200fps 4538 ft/lbs

250gr SMK

340WM 2860fps 4531ft/lbs
338LM -- 2955fps 4837ft/lbs

Using 90grs of Norma MRP powder, 250gr Woodleigh SN for the 340WM 2986fps 4939ft/lbs

Same powder using 250gr Hornady SP in the 338LM 2930fps 4756ft/lbs

Superiority seems to fluctuate between the two depending on which bullets are used. There's no question both are accurate, hard hitting and expensive, so why all the research into the 338 Lapua Magnum? Why not just change the shoulder angle of the older 340 Weatherby?

Headspacing is probably the answer.

Jimro

I've been wonderiing this stuff too. The 300 Weatherby is far superior to the 300 Win Mag and I truly feel could hold it's own against a 338 Lapua. The 340 Weatherby is a quality round also, just expensive to shoot. Roy Weatherby was a genius in his own time. Only problem is that nobody makes match ammo for them and there's not a lot of reloading data for them, as well as they are barrel burners. They shoot the 300 Weatherby in 1000 yard matches in Pennsylvania quite alot but if you keep looking a the benchrest boards they are being replaced by the 6mm
.
I'm sitting on a Kreiger 28 barrel for 300 Wby...I just cant' decide if I want to try to build this rifle on a Rem 700 or a Howa action. I would love to actually get a Wby Mark V action and build it cause of the 9 locking lugs...however very limited by that. Anyway a Mcmillan A5 is several months in the works and I've not really decided how I want to spend my money. I hope to one day get to Fleas reloading course and seriously work on this round. He is supposed to have shot in Penn quite a bit and I hope he has some good loads f0r this. But I definitely hear you...Weatherby has always been there and should not be discounted.

Belted ammo=yuck! Headspacing problems=belted ammo=yuck!

Not saying that belted ammo can't be reloaded and shot with some degree of accuracy, it's just easier to do with a normal cartridge.

Belted ammo=yuck!


Scott B

The 300WM and 7mm Mag are both belted and very accurate as well as popular. I for one never had a problem with headspacing problems. The .300, .340 and .460 Wby magnums are all serious hard hitting rounds. Even the .257 Wby out performs all the other .25 cal rifle rounds.

I own many belted cartridges....that's out of the way.
I like cartridge that'll do the same thing without the belt for reloading.


Here's a visual comparison for you:


Case capacity for the 338LM is 111 grains of water....
Case capacity for the 340WM is 93 grains of water....
The velocity for the 200gr Nosler is a little fast, my research shows it at 100fps slower for the WM....3145fps?(might need to look at your reference to get this one cleared up)
My 338LM will do a Hornady 200grainer at 3335fps without breaking a sweat....
Is there a loading available to push 300grain SMK's out of the Weatherby....safely?



They both are fine cartridges, I don't really care whom developed them for what kind of money. Cause when it comes down to it, we'll all end up in the dirt one fine day...nd I won't be dragging a bag of cash behind me.


Scott (got bored this morning) B

SR -

What are you meaning by changing the shoulder angle for the 340? I can see how this comes down to the .30-06 vs. .308 thing as far as casing design. Now I'm no expert...but my gunsmith is...and I've talked with him for hours about building a system for a 300 Wby cartridge. He's an older man (73) and has been doing this for 50 years. He has pictures of him and Roy Weatherby and he says he knew him quite well. This old man goes to SHOT every year and is very well read and updated on current technology, so I believe him. And what he told me as far as the Weatherby casing designs is that Roy Weatherby designed them all to have a certain neck angle and all this other stuff that I don't really understand...through his own R&D...that somehow allowed him to get longer barrel and throat life out of his magnum cartridges. There probably could be some improvements made on this casing design but I guess at the time it was the best fit they could come up with for the rifles.