338-300 Win Mag

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thesheepdog

New member
Hello everyone,

Does anyone have on of these loadings?
I heard about this recently and can't get my mind off of it.

I have 338 barrel blank that I'm tempted to chamber on this caliber loaded to CIP length. And just so you know, I have a 338 Edge already...so spare me the comments that I should go with something else. :)

I like the idea of using 300 WM brass necked up to accept the long, high BC Berger 300gr bullets (loaded to 3.8ish")
 
M

Mobuck

Moderator
The short neck of the 300 Win mag case may not hold .338 bullets against the recoil of such a wildcat. Do you have something against the common 338 Win mag?
 
C

Crankylove

New member
The .300 Win Mag already has a short neck compared to other calibers, I believe Mobuck is saying that expanding the already short neck to .338 may not give a long enough neck to provide the tension/friction to keep the bullet in place under recoil for cartridges in a magazine.
 
H

hammie

New member
Expanding the .300 Win Mag to take .338 bullets would make the neck longer, but not that much longer. If I correctly remember my high school trigonometry, the neck length would increase to .2874, when necking up to .338. I've always "heard" that necks should be at least one caliber to provide enough friction to keep the bullet from moving under recoil. I guess in this instance, that would be .330. As data points, the neck length of the .338 win mag is .331 and the neck length of the .338 ruger compact magnum is .320.

I don't know how hard and fast that rule is. The neck length of the .300 win mag is .264, which is well under .300. However, I've never had problems with bullets moving in my S&W 1500, .300 win mag. I almost always shot un-crimped 165 grain bullets. The few 180 grain bullets which I used, were crimped.

(@crankylove: Hello! Haven't seen you post for a while. Hope you're fine.)
 
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green_MTman

New member
military snipers and target shooters shooting out past 1200 meters need the sectional denscity of a 300 grain spitzer to be stable in the wind.

but for hunting with modern bullet technology a 30 caliber 200 grain swift A frame hits harder and penitrates as well or better than a .338 using older bullets.even the 175 gr 7MM bullet is 1200 lb Bear worthy with good bullets and good handloading.

why not just use .300 magnum or a 7MM ultra magnum,why invent a new .338

i would like a .30-378 WB someday what can .338 do that it cant
 
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thesheepdog

New member
jmr40 said:
I'm not familiar with this cartridge. What do you expect to gain over just loading 338 WM?
Click to expand...

The 338 WM has a shorter case than the 300 WM. This equates to nearly 10gr difference in powder capacity. By using the 300 WM brass over the 338 WM Brass, I'm able to push the bullets a little faster.



green_MTman said:
military snipers and target shooters shooting out past 1200 meters need the sectional denscity of a 300 grain spitzer to be stable in the wind.



but for hunting with modern bullet technology a 30 caliber 200 grain swift A frame hits harder and penitrates as well or better than a .338 using older bullets.even the 175 gr 7MM bullet is 1200 lb Bear worthy with good bullets and good handloading.



why not just use .300 magnum or a 7MM ultra magnum,why invent a new .338



i would like a .30-378 WB someday what can .338 do that it cant
Click to expand...


I've heard the question "why?" often. Well, I already have a 338 Edge and I've got a spare barrel in 338. I wanted to chamber the third barrel in a 338 caliber that has readily available reloading components while also able to fit in a magnum bolt face.
The 338-300 WM fits the bill. Being as the military just adopted the XM2010 and ordered 3.8 million rounds of ammo for it, I figured that the 300 WM is going to become more and more available with the possibility of Lake City brass. I don't give a rats behind whether the case has a belt or not. I've got a 338 Edge.
 
J

jmr40

New member
I'm not familiar with this cartridge. What do you expect to gain over just loading 338 WM?

The 338 WM has a shorter case than the 300 WM. This equates to nearly 10gr difference in powder capacity. By using the 300 WM brass over the 338 WM Brass, I'm able to push the bullets a little faster.
Click to expand...

Fair enough. Do you think the long 300 gr bullets combined with a longer case will cause problems with ammo being too long for the mag box?

Not being critical of your choice, just trying to learn.
 
T

thesheepdog

New member
That's a good question. My setup won't have these issues. This is a purposes built rifle using a Mcree extended mag folding stock (uses AICS/accurate CIP 3.85" mags)
I'll have the bullets loaded to fit this mag box and the barrel throated for the extended length.
 
H

hammie

New member
@sheepdog: There is so much duplication of ballistics in the current cartridge line-up, that I suspect we could eliminate half of the commercial cartridges and still be served none the worse. But where's the fun in that? There is much enjoyment is loading and experimenting with uncommon cartridges, and so I say if you want a .338-300 win mag, then ignore the denigration and go for it.

When I first read your proposal, I wondered if you would lose the advantage of increased case capacity due to the short neck and the necessity of seating bullets so deeply. That's one of the problems I run into with heavier and longer bullets in my .300 win mag. However, maybe you will bypass that problem with a longer magazine and throat, as you have planned.

My only other observation is: wouldn't the recoil be brutal? My idea of a long range cartridge is one of the 6.5's or a .220 swift. Fewer loose dental fillings and detached retinas that way.
 
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green_MTman

New member
@sheepdog

if you love it do it.

i did not need a 6.5-55 swedish mauser when i bought it,the 7MM-08 or .260 rem is more practical.l but the 6.5 swede so much more FUN
 
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thesheepdog

New member
Yeah I am really looking forward to this cartridge.
It should exceed the ballistics of a 300 WM loaded with 230 Bergers. And I won't have to fireform cases or anything weird like that. Just neck up and shoot.
That'll give me a very nice long range setup in the event brass is hard to come by for the Edge.
 
M

Mobuck

Moderator
It is commonly considered that the neck be at least one caliber long to properly hold bullets w/o requiring crimping.
 
J

Jimro

New member
If you can really get an extra 10 gr of capacity it might be worth it from a ballistics standpoint. These are just "back of the napkin" guestimates, so use anything here at your own risk, I make no claims for safety or performance.

A 338 Win Mag with a max charge of IMR4350 listed by Hodgdon nets 2,420 fps at 64gr compressed. That works out to 37.4 fps/gr.

The 338 Win Mag has 86gr case capacity. 64gr IMR4350/86gr H2O = 74% fill rate. An additional 10gr of H2O capacity for you wildcat times 74% gives 7.4gr more IMR4350 to compressed. So an additional 7.4gr of powder would be 71.4gr, 71.4gr times 37.4 fps/gr = 2,670fps max charge with IMR4350, from a 24" barrel.

Food for thought anyways.

Jimro
 
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Magnum Wheel Man

New member
I'm all for the custom stuff :)

how much actual difference is there between the 8mm Magnum & the 338-300 ???

hmmm. thought there would be heavier 8mm bullets, but looks like 220 grain is about the heaviest of anything with a decent ballistic coefficient...

maybe 338 - 8mm mag :confused:
 
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