Lapua bolt face on a 700

[JJMoody]

That's what I figured. I had a MKV 340 and was planning on rebarreling in 300 NM but my GS said he wouldn't do it.

 

[shortgrass]

Another thing that should be considered, besides bolt diameter, is the major diameter of the barrel tenon thread. With the larger O.D. of the Lapua and the Norma a larger tenon diameter should be considered, also. 1 1/8" diameter will increase the chamber wall thickness for these larger diameter cases.

 

[MagnumManiac]

This debate has it's points.
I have a CZ 550 magnum in 505 Gibbs, the bolt face has a minimum wall left, don't see it being a problem. The case is still positively held.
I also built my 338/416 Rigby Improved on a CZ 550 magnum action. There's plenty of meat in the bolt face left to handle the .590" rim.
I just copied my 416 Rigby in the same action, opened the .532" face to .590" and replaced the extractor. Only issue was that going from .458WM to .416, the ejector is shorter and the case rim hits the action before being ejected due to the larger diameter. It's now fixed with a longer ejector blade.
My 338Edge is built on a Rem 700 that started out as a 300RUM, very difficult rifle to obtain here in Australia.

Cheers.

 

[yobuck]

About 1973 I bought a Hart#4 single shot sleeved action having a standard magnum bolt face. The bolt although made by Hart, was a 700 copy with a different handle. Howard Wolfe chambered the gun for
the 300 Wby case necked down to 7mm. A few years later I approached him about rebarreling it and making it a 30x378. He just shook his head no, said the bolts not big enough, and that was that.
A couple years later we met up on a hillside someplace, and out of the blue he asked if I was still interested in doing that. He knew I had the right powder, and added that I couldn't load it as hot as some of the guys I knew having one of his actions,
which he had by then stopped having produced.
What he did was to turn down the rim on the 378 case so it fit the standard mag boltface, which is also what Remington later did with the ultramag.
Fact is, with the load he insisted I use, that's exactly what I had.

 

[Pdvdh]

The force against the bolt face is the same in a specific cartridge and load whether the rim of a case is rebated to a smaller diameter or left at the larger diameter.
Reducing the rim diameter may allow better function on some bolt faces.
Reducing the cartridge operating pressure will reduce the force applied to the bolt face, of course. Which would explain why the gunsmith would insist on a lower operating pressure.
Most gunsmiths aren't going to chamber a rifle for a cartridge that can't safely be loaded to normal maximum operating pressure. Because future gun owners/reloaders will undoubtedly exceed the lower pressure spec'd by the gunsmith. And then blame the gunsmith for any damages. Too much risk and increased liability exposure.

 

[Gregg C]

Late to the dance....
Question- A 300Wby Mag makes the same pressure as the 338 Lapua. If a .750 bolt works for the Weby, why not the Lapua ? The recess in the bolt face is bigger, but the bolt it self is the same diameter. What does the recess do except locate the cartridge?

 

[sable tireur]

Gregg C,

There is some math and physics which go into any real explanation as an answer to your question. Rather than reinvent the wheel, here is an explanation from Dan Lilja:

http://riflebarrels.com/a-look-at-bolt-lug-strength/

Here are some illustrations to go along with another analysis:

https://www.varmintal.com/abat85.htm

Take your time and read carefully.

 

[yobuck]

Late to the dance....
Question- A 300Wby Mag makes the same pressure as the 338 Lapua. If a .750 bolt works for the Weby, why not the Lapua ? The recess in the bolt face is bigger, but the bolt it self is the same diameter. What does the recess do except locate the cartridge?

The 300 Norma case is the same as the 338 Lapua as for head dimensions. The Norma was designed around using 700 Rem actions and many are using it on those actions. Take a look at the bolt face and there is very little left of the rim. But then the push feed Mauser actions along with model 70s have no recess at all, just a flush bolt face with the side extractor.
I personally prefer a larger bolt diameter for the larger cases, and would prefer a Weatherby action over a Rem for that reason for those type cartridges. The argument remains however as to the actual strength factor.

 

[Gregg C]

Apparently I've got some homework to do. And some tough thinking . In my ignorance, I had a 338 378 Wby built on a Savage 116, swapping in a Savage bolt head for the 338 Lapua bolt face. Has worked up to this point, here being close to 1000 rounds. Amazing how much confusion( or caution ) a little knowledge can generate.

 

[shortgrass]

The 300 Norma case is the same as the 338 Lapua as for head dimensions. The Norma was designed around using 700 Rem actions and many are using it on those actions. Take a look at the bolt face and there is very little left of the rim. But then the push feed Mauser actions along with model 70s have no recess at all, just a flush bolt face with the side extractor.
I personally prefer a larger bolt diameter for the larger cases, and would prefer a Weatherby action over a Rem for that reason for those type cartridges. The argument remains however as to the actual strength factor.

The Mausers you speak of are "controlled round feed" as are the pre-64 model 70 and Model 70 'Classics'. Some of the post 64 Model 70s are push feed and those have a recessed bolt face like the Rem. 700. The pre-64 and the "Classics", as well as the Mauser '98 do have a bit of a recess just not as deep as the push feed Model 70 and the push feed Rem. 700.

 

[sable tireur]

Amazing how much confusion( or caution ) a little knowledge can generate.

This is the chance you take when you post a question on a public forum. There are no controls other than the basic rules which get applied to the responses. Anyone, knowledgeable or not, can respond as long as they are in compliance with the forum rules. Many responses simply parrot what they have read on other forums or have heard in the LGS. The depth of their knowledge is zero and their experience is even less...

Confusion and caution are easily separated. Confusion can be generated by those without the depth of knowledge and experience to relate the technical information correctly. Those who express caution are certainly entitled to do so since it gives everyone a chance to pause and reexamine the technical information. However, those who express caution often couch that caution as a warning that their opinion is more correct than others with the same or better experience and knowledge base. This makes those with a differing opinion pictured as being careless and lacking in safety.

Good, sound knowledge trumps all when combined with the proper training and experience.

 

[Gregg C]

This is the chance you take when you post a question on a public forum. There are no controls other than the basic rules which get applied to the responses. Anyone, knowledgeable or not, can respond as long as they are in compliance with the forum rules. Many responses simply parrot what they have read on other forums or have heard in the LGS. The depth of their knowledge is zero and their experience is even less...

Confusion and caution are easily separated. Confusion can be generated by those without the depth of knowledge and experience to relate the technical information correctly. Those who express caution are certainly entitled to do so since it gives everyone a chance to pause and reexamine the technical information. However, those who express caution often couch that caution as a warning that their opinion is more correct than others with the same or better experience and knowledge base. This makes those with a differing opinion pictured as being careless and lacking in safety.

Good, sound knowledge trumps all when combined with the proper training and experience.

My apologies, it seems as tho my reference to confusion, caution, and a little knowledge was directed towards anyone on this thread. Such is not the case. I was talking entirely About Myself. What I should elucidated more clearly is that
I made a decision to build monster cartridge rifle on an action not designed for said case. Without seeking input from anyone who would have more knowledge and or experience, I should add.
Then I learn that many folks, that I have come to respect , on this website would have advised against such a build. I have gained " a little knowledge" by reading here. On this subject, at this time, that is DAMNED little knowledge, and that has led to My "confusion". Which, when coupled with the tiny amount of knowledge I have obtained, leads me to be cautious. Something along these lines. Is the **** thing gonna blow up in my face i dunno maybe i better stop shooting it till i figure it out. Pretty much exactly like that, in fact. In no way did I mean to denigrate any one . Nor was I being sarcastic. Again, if I offended, my apologies. Such was not my intent.

 

[sable tireur]

I don't think you owe anyone an apology especially me since I wrote the above as an observation to the comments and I did not take them as criticism. There are apparently two sides to every coin, you and I have just proven that as a case. Your and my observations are separate and different depending on how we read the details.

I've stated this at least a couple of times, it is very difficult to get all the words to say exactly what you mean each and every time you write them. I find this often when I try to write too fast and don't get the idea(s) presented just as I wanted to. Then I end up explaining or apologizing. Part of the trials and tribulations of writing on forums on the internet.

 

[Gregg C]

Well that makes sense. I try very hard to not come across as offensive. I will not engage in heated argument on the internet and intensely dislike those who seem to go out of their way to pick a fight. And yet, the written language does not lend itself well to facial expression or other visual prompters. I could well be mis construeing what is being said, after all !