Large .338s... potential accuracy?

[GMBshootingclubM60]

I'm new here and still searching all the forums for info. If this has already been discussed, please point me to it.

Of the .338s that will fit in a Weatherby MkV action with the 378 boltface, is one known as the best for accuracy? I know the .mil uses the Lapua. I also read here in LRH that the rebated .338 RUM is a good shooter.

It looks like the Excaliber or the Kahn are about as 'big' as I could go with this action.. how are they with the high BC bullets?

And.. there is a suspicion that the Weatherby offerings, with the long freebores, may not do well in the accuracy arena when using the long-nosed, short-bodied high BC bullets?

And... I'll be single feeding, so OAL is not a problem.

 

[Long Time Long Ranger]

I have done most all of them and they all are very accurate. I couldn't pick one over the other. The key is get a gunsmith who is very familiar with doing the particular cartridge you decide on and knows the wby mk 5 action and has a lot of experience with it.

 

[Chas1]

Anyone of them you mentioned is very accurate so long as the rifle is built very well and you do your part, so I'd pick the one you feel best meets your needs/criteria and as LTLR said find a reputable smith who's built more than a few in that cartridge with that action.

IMHO I can't stress enough how important it is to define your criteria as the better you define it the clearer your choices may become. You may be surprised to find out that the 338's aren't actually what you need or maybe you do so I'd first define criteria.

 

[GMBshootingclubM60]

So, if cost of shooting is not a factor, the Excaliber could be made as accurate as a .mil Lapua? It would be able to push heavier bullets, too.

 

[winmag]

Cost is one issue, so youve got that covered, but I think what Chas was saying was; in order to narrow down the choices what do you plan on doing with it, and what is your definition of accuracy? Will it be a L/R hunting rifle or a B/R comp rifle, is it gonna weigh around 12-15+lbs or do you want something lighter, Are you up to the challenge of fireforming cases and using brass with another headstamp, or do you want readily available brass, Custom dies or off the shelf, what velocity and what wt. bullet are you wanting to use, and the list goes on for ever......The real neat thing about a custom is all the choices, but its also part of the aggrevation. Whittleing it down little by little by defining your criteria, or intended use only helps make your decision easier. I think thats what Chas was getting at.
I only own 1 338, and its a 338win mag. so I dont have hands on experience with the big boys. Sorry.
You may wanna check out J E Custom and see what he has to say about the bolt face. He did a post on bolt face diameters a while back that got turned into a ''sticky'' in one of the threads.
Im goin out on a limb here and gonna say the first 4 guys Id talk to about 338 wildcating, in this case, would be; LongTimeLongRanger(for his wby knowledge and 338wildcatting), J E Custom (for his smithing and knowledge), Shawn Carlock(highly respected L/R 338 shooter and wildcater),and Kirby-AKA-Fiftydriver (for his smithing and reputation as king of 338 wildcats).
LTLR already chimed in so that leaves 3. Good luck, hope you find what your lookin for.

 

[trueblue]

GM,
If you already have the M5 action, I would build either the 338 Norma or Lapua on it. Both of those have excellent brass.
The 338 Norma brass is as good as it gets.
If you don't have any experience with 338's, no need in going any bigger than that.
Only other thing to do is get a custom barrel and find a smith to put it together for you.

 

[lazylabs]

I have a 338/378 and I am happy with it. It has a shilen barrel and shorter throated than factory but no changes to the case shape. It will shoot under 1/2" with several bullets. It's on a rem action so I have no experience with the weatherby.

I have a 338 rum and a 338/408 in the works. If you are looking for a single all around gun the lapua or one of the improved lapua designs would be very hard to beat. Having the best off the shelf readily available brass is a great advantage.

Like it was mentioned before defining exactly what you want is the first thing to get solidified. I had the 338/378 first and while it's fun to shoot with a 30" heavy barrel it's not very portable and can't really be shot without any setup time. That was the reason to then get a 338 rum. Its the light portable sporter gun that is for shorter range but can be shot off hand or "setup" for a little longer shot. The 338/408 is going to be for over 1K experimentation and with a 36" barrel it I don't see it getting very far from the truck. There is just a trade off for every choice.

 

[angus-5024]

I remember asking the same questions that you are about 3 years ago. I love the big .338's and every time I think about getting a new rifle, its a .338. I think that the others hit the nail on the head with getting a definition of intentions. For me personally I have limited funds for both equipment and cost of shooting. I hunt in the high country, usually on foot. I chose a .338 RUM (remington action). Its cheaper to buy (XCR model was around 1k CAD), brass is way cheaper (though it doesnt last as long) and the recoil was exceptable in a 9.5 lbs rifle. If I had the $$ i would probably go with a Wby action and build a Lapua improved sitting around 13 lbs-15 lbs. If you just wanna shoot way out there go bigger and heavier. its all gotta be buit around your intentions.

 

[Chas1]

Winmag, your spot on. That's exactly what I was implying. I too had the bug for a 338-378 but the more I defined my criteria and the more I learned...much of it here and some elsewhere then the less a 338-378 made sense to me. Not that it isn't a fine chambering but, not for me based on my criteria. There were atleast several dozen things that defined my criteria and it was a process that took about a year...of coarse I was learning along the way too. But, do your homework and define your criteria as finite as you can and you'll be much more assured of being happy with the end product.

 

[GMBshootingclubM60]

So LongRanger and Chas1 are saying that the Excaliber and the Kahn can be coaxed to half-minute accuracy, probably with less than max loads? This would give MVs better than a Lapua, for example.

So far, no one has said that the long freebore on the 338-378 is an accuracy problem.

 

[specweldtom]

Just my opinion, but.....

If you want a 1000 yd, or less, rifle around 9 lbs scoped, .340 Wby in a Mk V or a 700 action. (with a muzzle brake). 210 - 250gr bullets.

I think the .338 Lapua is sort of in between the .340 and the .338 RUM in performance. I don't have any experience with the Lapua, but it has a very fine reputation for accuracy (and quality brass).

Next up would be the .338 RUM at about 10 lbs with a brake on a MK V or a 700. 210 - 250gr bullets. Maybe try some 265's or 300's.

Then a .338 x .378 Wby (only on a Mk V) at around 12 lbs. 225 - 300gr bullets. Put a brake on it if you want to shoot very many of the 300gr bullets.

The biggest practical .338 on a Mk V is the Excalibur, probably around 15 lbs. 250 - 300gr bullets.

The .338 RUM would be the cheapest to feed, the Excal the most expensive, with the .338 x .378 close behind. I don't know where the Lapua would fall.

The .340 Wby, .338 Lapua, and .338 RUM have the reputation for being fairly easy to dial in accurate ammo. The Excal is not as finicky as you might think, but the .338 x .378 can be fairly tricky to load for. The Lapua brass should be the longest lived, but I can't verify that. Norma brass in a really good chamber will loosen the primer pockets long before the body itself is fatigued. Speaking of chambers, a good chamber will be tight enough to feel the bolt closing on new brass. Many times, these chambers won't let the bolt close on a go-gage. As close to no headspace as you can get and still accept new ammo.

Short-throated boomers can get scary with hot loads. I strongly recommend the factory or SAAMI chamber dimensions. I have seen a custom short-throated Wby .30 x .378 that could not shoot Wby factory ammo. Blown primers and stuck (ruined) cases. It had to be hand loaded with reduced performance loads. I also saw 2 other custom .30 x .378's with factory dimension chambers (lots of freebore) that could shoot 5 shot groups under 1/4 moa. Best for one of them was a .091", and for the other, a .204". Both were near max loads, (avg 3 shots to loosen the primer pockets). Not too shabby.

All the .338's listed are capable of sub 1/2 moa groups, the Excal included. Autorotate knows this cartridge better than anyone else I know of. Maybe he'll see this and jump in.

Again, some of this is experience, but the caliber choices and ranking are just my opinion.

Good hunting, Tom

 

[GMBshootingclubM60]

I owe Autorotate already for the Weatherby 'drop box' magazine idea, which adds a round to the capacity for 378 size brass.

I guess the deal will be to start a build on an Excaliber for me in a Mk 5. I'll be ready in a year or two and the good 338 bullets that are coming will be there just in time (I hate that stupid phrase)..

Been reading the Berger 300 thread.

 

[Chas1]

Sounds like you made a decision to go with the Excaliber. Keep us posted on how it goes.

 

[GMBshootingclubM60]

Anybody got any Excaliber brass hanging around? Is Midway the best deal or is there another source that's less expensive?