mod 70 .338 win to .340wby

[shortgrass]

Magazine length is not the problem, it can be easily delt with. The loading/ejection port can be where the more serious problem lies,,, depending on which action you have... I'd thought about a 7STW on a 70 that was originally 7mag. Not enough port to pass a loaded round.

 

[Boman]

I wondered about that as well. How do I find out

 

[bullfrog]

Rear scope mount holes have a .330" spacing on "express" or "magnum" actions such as 7mm STW, 300 weatherby, 375 H&H or other full length magnum actions. The port can be lengthened by your gunsmith to accommodate the longer rounds.

 

[MagnumManiac]

Winchester Model 70 Classic actions come in 2 lengths; 'standard' which is 3.400" in magazine length, and 'magnum' which is 3.610" in magazine length. The 340 Weatherby has a COAL MAXIMUM LENGTH of 3.700". The 338RUM has a COAL MAXIMUM LENGTH of 3.600". Both of these cartridges are too long for a standard length action.
If you have a standard length action, as in what the 338WM is built on, not only does the rear ring need to be shortened/opened, but the bolt stop has to be moved to the rear by a 1/4". This will be the same cost as a complete second hand rifle with correct action length.

A Kimber 8400 has a 'magnum' length action, even with standard length cartridges, they have a block in the mag well for the shorter cartridges. You can simply build a 'magnum' length cartridge into an 8400 by removing the mag block.

Another cartridge that would fit a standard length action is the 330 Dakota.

Cheers.
gun)

 

[Boman]

Thanks magnummaniac. I guess that settles that

 

[wapiti25]

I have a M70 Classic that was purchased in .338 win and the mag is shorter than I like, even the 200gr bullets have to be seated past the neck/shoulder junction. I bought another mag and reworked it and gained about .100" of length.

 

[436]

Hey guys, I am thinking of buying a Winchester model 70 extreme weather (stainless) model in .338 win. But what I'd like to do is turn it into a .340wby. Besides the rechamber what else would need to be done? Thank you

Much has already been said, many good points and tips here.. but I never saw what barrel length you're going to put the .340 Wby in. From what I understand about the .340 Wby if it's less than a full 26" inch you might as well stay with the .338 WM. a great cartridge in it's own rights.
Just asking.
Cheer's
436

 

[Boman]

At this point I'm leaning towards the kimber 8400 montana. As much as I'd love to go with a winchester I called them and not only were they less than helpful they were downright rude. A truly sad situation at winchester.

I'll probably go with a 26" barrel although I've had a 340wby with a 24" barrel and it was within 50fps of my dads 26". The smart way to go is to just stay with a 338win but I just like the 340.

 

[MagnumManiac]

At this point I'm leaning towards the kimber 8400 montana. As much as I'd love to go with a winchester I called them and not only were they less than helpful they were downright rude. A truly sad situation at winchester.

I'll probably go with a 26" barrel although I've had a 340wby with a 24" barrel and it was within 50fps of my dads 26". The smart way to go is to just stay with a 338win but I just like the 340.

Hope it works out for you, I love my 338, it's great. But my 340 gets used just as often and the only real restriction is rifle weight, it weighs a full 1.5lbs heavier than my 338.

Cheers.
gun)

 

[Boman]

Thanks Magnummaniac,
What are your rifles? Do you prefer the extra weight?

 

[MagnumManiac]

Thanks Magnummaniac,
What are your rifles? Do you prefer the extra weight?

Both are Win Model 70 Classic Stainless, one standard length and one magnum length, the biggest difference is in barrel profile and stock weight, both wear HS Precision stocks and both are switch barrels. The 340 is set up with a target style stock and the 338 is a hunting style stock. I have no preference when it comes to weight, my new 338 Edge,which is unfinished, will come in at over 14.5lbs once all the accessories are finished, it's on a Rem Sendero action.
The lightest rifle I own is a Kimber 8400 Select in 300WM with a leupold VXIII 3.5-10×40, it weighs under 8lbs.

Cheers.
gun)

 

[Boman]

Very nice. I like your taste in rifles. I've always been an ultra light rifle guy. I'm now getting into heavier rifles. Thanks for your help