338-378 M700

[Brent]

I have a Rem.700 LH in 358 Norma, I want to rebarrel to 338-378 at 36" for a single shot LR rifle only .

A couple of questions though, is the bolt face large enough? What dia. barrel is the largest you would go without the use of a barrel block on a 36" tube? Is there enough material under the barrel threads with this large case in a lightweight or heavyweight tube? Anything else I may not be considering too?

 

[Darryl Cassel]

Brent

Don't try it on a Remington action. The bolt face is not big enough.

Later
DC

 

[rifletuner]

As noted by Darryl, the bolt face is not big enough for the 378 cartridge (nor the 416 Rigby which is essentially the same, but without the belt). That however is just the beginning of the story. The action is not big enough to adequately support a cartridge case of that size, and neither will the Rem bolt lugs.

In addition, I would suggest that the action threads and bedding area of the Rem 700 would not support a barrel of 36" in any but the narrowest profile. A correctly block bedded barrel would circumvent this problem.

My own view (which I know will not be shared by all others) is that a Rem 700 is not suitable for cases bigger than the 375H&H belted magnum.

Fergus

 

[AFP]

I think stuffing a 338-378 sized case in a 700 is a bad idea (using an M-70 would also be a bad idea). The 700 is my favorite action, but I understand it's limitations. I was very skeptical with the Ultra sized chamberings, but after enough guys got the 338 Ultra and had good results, I one built up. We installed the long/wide magazine box. Until I get the BDL floorplate designed for the Ultra's, my magazine capacity will stay at two--which is enough. My Ultra feeds flawlessly, and is showing some accuracy potential. So far I have shot a .2245" 3-shot group with 250 Partitions, but .6 to .7 is more the norm.

You could build up a 700 in the 338 Ultra and get good results. I don't know about the barrel length issue. I do have a 28" barreled 300 Win, and I have heard of 29-32" barrels on 700s. If you wanted to use a commerical action and build a 338-378, the MK-5 would a logical choice.

Blaine

 

[Brent]

Thanks for the info everyone. Wish I still had my Ruger #1 378wby now. The stainless one may be in the works this time.

 

[Celt]

The 700 would have a couple problems like the bolt face. The bolt face diameter is such, that it would leave the bolt nose wall thickness a little thin. There is also the fact that you would have to do a bit of milling on the action and make a new mag. box to accept the ammo, modify the bolt stop and rear ring to allow reliable ejection.

The lugs I am sure would hold up, as they are no weaker than a MKV Weatherby, the action as well would hold up, as it is actually stronger and thicker than a Weatherby. The barrel threads are as long as a weatherby and have worked just fine in the past for me building rifles with 28" barrels with a muzzle dia. of .905

It's too bad Remington does not make a little longer actioned, thicker bolted action for such rounds, but then again, the 300 - 338 RUM, a 300 Rum necked to 338 and with a 30 deg shoulder is every bit a 338 / 378 with the exception of being more inherantly accurate.
The 338 RUM is not quite ballistcally what the big Weatherby is, but accuracy is outstanding! with less recoil, longer barrel life and longer case life.

Celt

 

[Brent]

Well I just talked to my brother, he's having his Rem. 300 RUM rebarreled to 338/378 with a 30", .750" at muzzle Pacnor 1-10 twist. Dave at Nitro Gunwoks says it will take alot of work to feed if the single shot isn't enough for him. The bolt face margin will be about .050" instead of .075". I believe it will use a Sako extractor.

I understand he has built the 30/378's with a max length 30" barrel not blocked on the Rem. 700 with no problems.

I have a few questions though.
How much margin on the face is necessary and why?
Does this margin do anything other than capture the head for feeding and extraction?
Does the barrel thread diameter leave the chamber walls to thin?
If so, how much is to thin?
Thanks for the help. Sorry to prod for another deeper explanation, that just my logical way I guess.

 

[PrimeTime]

Brent-
Go to Lilja Barrels website and read he article Dan Lilja wrote about using a 700 for the 378 and 416 Case. I wouldn't recommend it from everything I have read.

 

[Brent]

I'll go check out what Dan has to say too. Thanks.