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338-378 weatherby

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Unread 10-05-2006, 10:09 AM
Gold Member
Join Date: Jan 2005
Location: Searcy, Arkansas
Posts: 700
Re: 338-378 weatherby


I have been shooting the 338/378 for several years. I have since had mine turned into a wildcat version called a 338 Kahn, but that is another story......

I too started out shooting 200s and 210s because I thought it was way cool to get 3500+fps. Now I am firmly on the side of the others who have advised you to go to a heavier bullet. Try the 250grn SMKs and 300grn SMKs. Not to try to start that argument over, but although the SMKs are match bullets they will do just fine on deer and elk. You are simply not taking full advantage of the awsome power of such a large case until you step up to at least a 250grn bullet.

I am loading 103 grains of RL25 with 250 SMK in my 338Kahn. You might start with about 101 grains and work up. You may be able to go even higher than 103 since your factory barrel has freebore that my barrel does not. With the 300 SMKs, try 110 grains of US869 and work up from there, 103 grains of H50BMG is a good load as well. You may be able to work both those powders up considerably from the loads given. I am being conservative here since I have not loaded those powders in 338/378 only my Kahn. For example I am loading 114 grains of US869 in it with the 300 SMKs. Velocity is around 2950fps. I get about 3170 fps with the 250 SMK and 103 grains of RL25. (FYI, I have a 30" barrel on my rifle)

Good luck and be carefull to work loads up slowly, 1 grain at a time and watch for pressure signs.......that is a powerfull round you are working with!
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Unread 10-05-2006, 10:20 AM
Platinum Member
Join Date: Feb 2005
Location: USA
Posts: 2,598
Re: 338-378 weatherby

I would think that US-869 might be worth a look in the 338-378 with the 300 SMK's........ [img]/ubbthreads/images/graemlins/wink.gif[/img]
range it,check the wind, dial in correction, aim and only one shot
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Unread 10-05-2006, 10:37 AM
Bronze Member
Join Date: Oct 2006
Location: Glendale, Arizona
Posts: 43
Re: 338-378 weatherby

I'm just getting into reloading what have people found to be the best powder to use in this gun [img]/ubbthreads/images/graemlins/confused.gif[/img] [img]/ubbthreads/images/graemlins/confused.gif[/img]?I will be reloading 200gr BST bullets.I'm thinking of useing imr 7828 powder.

[/ QUOTE ]

This is my .338-378 Weatherby Accumark. I topped it with a Leupold Vari-X III 6.5-20X 40 MM in Leupold mounts and rings. I'm having the best luck with WC-872 Ball Powder and the 300 Gr. Sierra Matchking Bullet. This combination has proven to be very accurate. The Accumark has a 1 in 10" twist barrel and will stabilize the 300 Gr. Sierra Matchking out to well past 500 yards. WC-872 Military Surplus Ball Powder is avaliable from Jeff Bartlett at www.gibrass.com Jeff is very good to deal with and if you buy 6, 8 pound jugs, he pays the Haz-Mat fee. This was one of the first targets printed when I first got it to the range. The Sierra 300 Gr. Matchking and the WC-872 have really tightened things up since then. Bill T.
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Unread 10-08-2006, 12:53 AM
Bronze Member
Join Date: Oct 2006
Location: Maryland, near Balmer
Posts: 34
Re: 338-378 weatherby

I never fails to amaze me that folks will go buy a monster masher round, like the 338/378, then want to shoot groundhog bullets in it. I have talked to the bullet companies and all of them say anything less than the 250, except maybe the Barnes X or Nosler are made for deer, and then if shot from the standard 338 or 338/06. Speed them up and are even less reliable. Elmer Keith designed this cartridge and said to use NOTHING less than a 250 in it. The lighter bullet lose velocity fast (someone here just said that), and lose energy fast too. Speer told me that no knowledgable 338 shooter would shoot anything less than the 250s and the 300s better. I hate to say this, but think a lot of the lighter bullet choice has to do with the recoil going up. But using a light bullet, like the 200-210s in the 338, especially one like the 338/378 akin to shooting 125s in the 300WinMag. Okay if you're hunting ground hogs, but not Elk. Elmer said the test of the load is, can you shoot an elk just forward of the left hip, if necessary, and find the bullet on the right shoulder, or preferably out the shoulder. You won't get a light bullet, regardless of type (maybe the Barnes X, but doubt even them) to do that. If an Elk has a belly full of wet grass and twigs, it will stop almost any bullet coming forward, but the high SD, heavy weights will go on.

I shoot a 338/06 and use only 250s and up, in it. Once you get the heavier bullets moving, they keep moving. One of the reasons we shoot 190s in our 308W in 1,000 yard matches, is, though it only starts at 2550, it is still sonic at a 1000 yds, whereas, the 168s at 2800 lose so much velocity, it is always speculative that they will stay sonic. Once the bullet goes sub-sonic, it is no longer accurate. The heavier bullet also retains energy better too. Obviouly, in my 308 case, a 190 still traveling at 1100 fps at a 1000 yds, is going to have more energy left than a 168 at 1,000 fps at that range, or even at 1,100 fps.
Go with the heavy bullet. The others are play things.
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