338/300win case capacity???

[drdougrx]

Hi All

A buddy just got a 338wm and picked up one of my 300wm cartridges to compare.  It appeared the neck on the 300win case was much shorter than the neck on the 338win.  Is this true and.....if I had a 300wm rifle and had it rebored to 338 and didn't address the chamber, would the resultant 338/300 cartridge have more case capacity than a standard 338win?

[Graybeard]

In answer to the last question first YES.

The .300 Winchester as I seem to recall is a bit longer than the standard of 2.5" more like 2.6" maybe and has a rather short neck as well. What that does is increase the case capacity up to darn nearly that of the .300 Whby but in a case short enough to fit more actions than the Whby will fit.

[deltecs]

Graybeard is absolutely correct.  The .300 Win Mag has a case capacity of 90.36 gr and the .338 Win Mag has 85.62 gr according to Donnelly's Handloaders Manual.  So any bore size increase in neck diameter will further increase the case capacity in addition to making the neck length longer.  I guess it is obvious I have way too much time on my hands.   

[drdougrx]

Well del...thank heavens you do!!

As always GB... I appreciate the time and the replies!!

[onesonek]

Graybeard is absolutely correct.  The .300 Win Mag has a case capacity of 90.36 gr and the .338 Win Mag has 85.62 gr according to Donnelly's Handloaders Manual.  So any bore size increase in neck diameter will further increase the case capacity in addition to making the neck length longer.  I guess it is obvious I have way too much time on my hands.   

While there is nearly 5 grs. difference, and this this would be fairly significant in a single shot, where the bullet can be seated out. But depending on the particular bolt gun, and mag length, bullet seating depth encroaching on the powder space, is going to cut that gain down some. Both the 338 and 300 pretty much are the same AOL. It would be an interesting experiment, just to neck up a .300 to .338 . Then stick a bullet in each to the same AOL, and weigh with water to  get a net gain. Just off the top of my head, I would suspect about a 2.5-3 grain gain. Which would possibly yield up to another 100-150 fps.
Dave

[deltecs]

Graybeard is absolutely correct.  The .300 Win Mag has a case capacity of 90.36 gr and the .338 Win Mag has 85.62 gr according to Donnelly's Handloaders Manual.  So any bore size increase in neck diameter will further increase the case capacity in addition to making the neck length longer.  I guess it is obvious I have way too much time on my hands.   

While there is nearly 5 grs. difference, and this this would be fairly significant in a single shot, where the bullet can be seated out. But depending on the particular bolt gun, and mag length, bullet seating depth encroaching on the powder space, is going to cut that gain down some. Both the 338 and 300 pretty much are the same AOL. It would be an interesting experiment, just to neck up a .300 to .338 . Then stick a bullet in each to the same AOL, and weigh with water to  get a net gain. Just off the top of my head, I would suspect about a 2.5-3 grain gain. Which would possibly yield up to another 100-150 fps.
Dave

As an experiment only, it might be interesting for a minute.  Yet, I'm not so sure this would be enough to warrant the cost of re chambering.  The .338 Win Mag is effective and sufficient for everything in NA and most game worldwide, I don't feel the need to increase the velocity any further.  If I need more punch, I'll go to bigger bore, probably .375 minimum.

[onesonek]

I agree Greg. I too would be happy with the .338 as is. I have long thought the .338 Win Mag as one of the best all-around cartridges for this continent ever made.  Although, if I where to have one, it would be on the Encore where I utilize the case volume to it's potential.
Dave

[drdougrx]

Thanks guys...I'm with you, but, I bought a .375 rather than a 338 because I have a nice 300win.  I was planning a brown bear and moose hunt in 2009 in AK, but, as luck would have it, my daughter will be going to an artsy fartsy college and I'll need to help with tuition.  I may buy a 338 anyway and I do so love the post-64 winchester m70's (why...I don't know).

[lgm270]

The  1969 Gun Digest contained an article by Chuck Hagel  with extensive discussion and load development of the .338 Win, the .338/300 Win Mag and the .340 Weatherby.   The .338-300 does indeed have more case capacity than the standard .338 Win Mag.

Hagel had loading data for the .338-300 Win Wildcat.   He used an M-70 full length action and rechambered for each round or re-barreled as may have been the case.  His big deal was to "long throat" the .338 Win and .338-300 so that bullets could be seated with the base of the bullet flush with the case neck.  The 338-300 was, as I recall,  right in between the .338 Win and the 340 Wby.  By "long throating" the .338 Win Mag, he bumped up speeds another 100 fps.  Elmer Keith did this too, using a full length magnum mauser action with his .338 Win Mag and long throating and seating out the Speer 275 Grain Bullet. 

I did this with a .338 Win mag  so that cartridge OAL was equal to the .375 H&H and I was getting 2,850 fps. with the 250 Gr. Nosler partition bullet.  I bought the rifle with the intention of rechambering for a .340 WBy,  but frankly the recoil with the .338 Win was as grim as I could stand and I could not see where another 100 or so fps provided by the larger .340 Wby  would make any practical difference.   

I don't know what you're going to do with the rifle, but personally I would stick with the regular .338 rather than fiddle around with necking up the .300 win mag case.  Maybe I'm getting to old for this  kind of thing, I don't know.  You're talking about re-boring an existing .300 win mag.   The last time I priced this type of thing, re-barreling was only slightly more expensive.  Personally that's the way I would go.  Every time I read some book and get a bug up my behind for some weird off the wall deal, I end up spending a lot of money and end up with something that is only marginally superior to what I could have bought right off the shelf.    Frankly if the .338 is not enough gun, you should probably go for the .375 H&H.

[Siskiyou]

Thanks for the topic it is turning on a few lights for me.  A brother has been telling me about his 8mm-300 Winchester.  One of the first questions I had for him was why he did not use the .338 Winchester case.  The response was that he gained a little case capacity with the .300 Winchester case and they were slight easier to pickup at local gun shops.

His cannon has a muzzle brake and he made the mistake of having the cap off it while deer hunt.  The muzzle blast just about put him and the deer down.  He told me the other day that he was loading a hundred “managed recoil” loads at around 2700-2800 fps using the 185-grain C-L bullet.  He can enjoy hunting deer with his managed recoil loads without the big bear blast.

[lgm270]

Thanks for the topic it is turning on a few lights for me.  A brother has been telling me about his 8mm-300 Winchester.  One of the first questions I had for him was why he did not use the .338 Winchester case.  The response was that he gained a little case capacity with the .300 Winchester case and they were slight easier to pickup at local gun shops.

His cannon has a muzzle brake and he made the mistake of having the cap off it while deer hunt.  The muzzle blast just about put him and the deer down.  He told me the other day that he was loading a hundred “managed recoil” loads at around 2700-2800 fps using the 185-grain C-L bullet.  He can enjoy hunting deer with his managed recoil loads without the big bear blast.

I know the feeling. We contrive to have the ultimate belted magnum and end up loading it down with "managed recoil" loads.   Does your brother know he can get 2,700 fps. with a 185 grain bullet with the 8x57 mm Mauser?

[Siskiyou]

I suspect he knows that he can get the less recoil with the 8x57, but that would destroy the fun of wildcatting and his gunsmith’s kids would not get new shoes.  He is just taking the advantage of one of the benefits of reloading.

He has a number of wildcats for the sake of wildcatting.  He has few rifles that he has not turned into a wildcat.  One is a 358 Norma Magnum, which he loads with 250-grain bullets.  When pain and discomfort is not the issue he will be found shooting a 6mm-06AI or a 6.5x55.

 

[lgm270]

I suspect he knows that he can get the less recoil with the 8x57, but that would destroy the fun of wildcatting and his gunsmith’s kids would not get new shoes.  He is just taking the advantage of one of the benefits of reloading.

He has a number of wildcats for the sake of wildcatting.  He has few rifles that he has not turned into a wildcat.  One is a 358 Norma Magnum, which he loads with 250-grain bullets.  When pain and discomfort is not the issue he will be found shooting a 6mm-06AI or a 6.5x55.
 

Good answer.