338/378 Wby or 338 Lapua

[ridge rider]

I am building a light weight custom 338 calibre long range rifle and am deciding between the 338/378 Wby or 338 Lapua.
The barrel is a 30" Benchmark ABS Carbon Fibre wrapped and will be throated for a 300 grain projectile either SMK or Berger.
Seekins magazine and bottom metal will complement the Defiance repeater action housed in Manners light weight carbon fibre stock.
Now I am sure this debate has already been through the forums before and wanting to take a somewhat short cut I am open to all suggestings, criticisms, for and againsts for each of the two cartridges above.
I have seen where Kirby Allen has done a lot of work using the Lapua cartridge.
I would like an honest opinion as to why the Lapua is perhaps the better option obviously being a non belted cartridge might be the primary reason for selecting this round.
I am aware Lapua brass is top quality stuff in comparison to Norma brass and the 338 Lapua has a better selection of reloading dies with bushings whereas there are no such dies with bushings available for the 338/378.
With that aside can someone offer other plausible opinions please bearing in mind that I already have a Weatherby Accumark in 338/378 with its standard Krieger barrel that will group 1/2MOA however it weighs 10 pounds 4 ounces with a 2.5-25x42 March scope, however I want to go lighter to use this rifle as a walk in and stalk rifle as well as having long range capability.
I have several hundred cases in 338/378 and top quality Redding reloading dies and need to be really convinced to move away from this cartridge in favour of the 338 Lapua.

 

[J E Custom]

It all boils down to case capacity and pressure.

The 338/378 has around 128 to 130 grains of powder capacity. The 338 Lapua has just over 100 grains depending on the powder.

The Lapua is a fine case and can take more pressure if a person wants to push it.

I have owned 1 rifle purpose built for pressure and found that Over pressure loads came with
to many problems. so I now look for the case that can do what I want with exceptable
pressures and stresses on the action.

Saying that you intend to shoot the 300 grain bullets sets the size of the case in my opinion
if you have a target velocity.

If I were going to build to use 300 grain bullets,3000 ft/sec+, with exceptable pressures I
would choose the 338 Excalibur because of the case capacity (over 140).

Expense is an issue with ether the 338 Lapua,338/378 Weatherby or the Excalibur,so that
should be not be a consideration.

The easest to load and shoot would be the 338/378.

The Lapua is at it's best when it has been improved with a 37.5 or 40o shoulder and with
the body blown out.This mod makes it comparable to the Edge with excellent case life.

So if you are going to shoot 300 grain bullets the bigger the case the better.

J E CUSTOM

 

[hammertyme]

I have both the Edge and the 338X378 Weatherby in 8 pound scoped applications. The Weatherby case with the much larger capacity comes into its own with the longer barrels. Both however will flat out hammer anything at most any range.

There is a smith in Idaho that has improved the 338 X 378 and he is getting some very impressive velocities. He is shooting extremely high BC cnc bullets of his own design at 250grs or so.

You are already set up for the Weatherby so I can't see any reason at all for backing down to the Foreign cartridge.

Neal

 

[ridge rider]

Thanks guys for all of your kind responses,
I thought I'd give this one some time before replying and thanking you all

Regards

RR

 

[Tikkamike]

This is my way of thinking. My dad has an accumark 338-378 I have a custom 338 lapua. Love them both. to me they are both reasonable to carry, my lapua is 11.5 lbs scoped, if I were going to do a light weight 338 I wouldnt have a 30"bbl id have a 26 maybe 24 in a remington based 338 RUM. Here is why. There are so many options for the remington you can make it as light as you want and look almost any way you want. the after market support for the remington is so vast its hard to go wrong.

 

[ridge rider]

This is my way of thinking. My dad has an accumark 338-378 I have a custom 338 lapua. Love them both. to me they are both reasonable to carry, my lapua is 11.5 lbs scoped, if I were going to do a light weight 338 I wouldnt have a 30"bbl id have a 26 maybe 24 in a remington based 338 RUM. Here is why. There are so many options for the remington you can make it as light as you want and look almost any way you want. the after market support for the remington is so vast its hard to go wrong.

Tikkamike;542241

Thanks for that bit of advice.
Earlier on I looked at the 338RUM option also as there is nothing wrong with that cartridge either, however since I was looking at more speed with less pressure this is why I went for 30" barrel to make the most of the 338/378 or 338Lapua capacity since the 26" barrel is too short for the slower Retumbo powder which I intend to load with.
I had already ordered my 30" Benchmark ABS Carbon Fibre wrapped in 338 calibre as I originally was just going to rebarrel my Weatherby Accumark.
My current 338/378 Weatherby Accumark weighs 11lbs 4ozs with a March 3-24x42 scope in Seekins rings and rail but I want to go lighter.
After having two rifles custom built rifles on Lawton actions with Jewell triggers in Manners stocks I entered a new world where I experienced a distinct difference in consistent accuracy and so I then decided to go for a custom action with more tenon than the MK5 action could provide and since Lawton were experiencing problems and could not provide me with another action for some time with this build I decided to go for a Remington clone and decided on the Defiance action for my next build which will allow me to tap into the huge aftermarket accessories for the 700 Remington.
I also opted for a lighter weight stock from Manners carbon fibre stock which should by all estimates bring the rifle's weight in at under 10lbs.

 

[Tikkamike]

How much will that barrel weigh? and in this case I have to say the 338 Lapua will not dissapoint. plus you can seat your bullets out much further with an extended magazine box because the lapua case is much shorter. my lapua with the wyatts extended centerfeed magazine box gives me 4" i cant even use all that up if I wanted to without putting the boat tail of my 300 smk in the neck. the 338-378 will have to have a 300 grainer stuffed in a little like with your accumark.

 

[JeffVN]

Personally I would add the 338 Norma Magnum to the equation. When using a 300 gr. projo (be it smk, Lapua, Hornady) and both are seated to magazine length, the 338 Norma Magnum has greater useful case capacity when compared with the 388LM, and will generally give better performance than the 338Lm.

JeffVN