Rem 700 vs Wby MkV in bolt locking lug comparisions....

[Jon A]

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*Why is the allowable torque spec always higher with a fine thread fastener when compared to the exact same fastener size that has coarse threads?

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Two reasons: The fine threads have more shear area than the course threads, and a bolt with fine threads has a larger minor diameter than one with coarse threads (threads not as deep, leaving more bolt shank intact). You'll find similar properties on splined shafts, etc, with different numbers of splines.

That's all I was trying to point out--in most areas where you'll find greater strength, you'll find more shear area. From Kirby's numbers above, there's less shear area so the same rules of thumb don't apply.
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So do you agree or not does having a circle supported in 3 spots around its circumference resist vibration better than one supported in two opposed places 180 degrees apart.

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Theoretically I do agree. But I'm no gunsmith so I can't comment on whether, in practice, lug contact can actually be made to take advantage of this with different actions. I personally like three lug designs (especially for their bolt lift) but as has been said, I wouldn't say they're needed.

 

[Hired Gun]

Kirby,
I agree this is one of the most interesting threads I've seen in awhile. That is unless it's one of your hunting stories or a picture of your work. Now back to the topic.

Consider this. I agree you may not get all three in each column bearing on the 9-lug action 100%. Say that just any one out of each row was only 50%. For peak accuracy and stability I content that with safe/sane loads that it is not necessary. For the .378 case or Ultra Mag maybe but with a regular 340Wby or smaller I don't think it's that big of deal. As far as canting the bolt head slightly you have to remember the massive .841" bolt shaft. That must help some for stability. My thinking on this is Weatherby also makes a 6 lug short action that has two even smaller lugs in each row and it must be rated to nearly the same pressure level as the 9 lug. They sell it for all 06' bolt face and smaller applications. The 240Wby, 25-06, 270 Winchester are all running magnum level pressures. I realize the .473" bolt face is smaller so it is receiving less load than a .531" bolt face.

I know at this point we are mainly just exchanging rhetoric but my motive is really to get you to believe that the Mark V is really worthy of putting your effort into and having the same level of confidence in the finished product to be able to tell me that it will shoot as good as it takes to make it interesting to you at 500+ yards like we talked about.

Shawn

 

[Buffalobob]

Sambo

It was Spring time of 1972 , I was just back from RVN and stationed at Ft Leonardwood until my time was up in June, and I would not even swear that turkey hunting was why I was loading FMJs at low speed. The project got abandoned needless to say. I enjoyed my stay there in the Ozarks and the crows and ghogs held a big party to celebrate my leaving.

 

[Fiftydriver]

Hired Gun,

Controling the bolt shift, totally depends on two things, Squareness of the bolt to receiver relationship, that being bolt face, bolt lug surfaces and receiver locking lug surfaces.

The other thing is bolt body fit to the receiver. Its the clearance between the bolt body and the receiver which either limits or allows the bolt to shift laterally while under stress.

This bolt shift is greatly eliminated of not totally eliminated with a properly trued receiver but bolt diameter alone has little to do with this.

As to the smaller diameter six lug design, there is DRAMATICALLY less bolt thrust with the .470" case heads. As the case head diameter increased the stess on the bolt and rifles increases expidentially.

This is why it is significantly harder to get a large cased round to shoot extremely accurately then a small cased round. To get a round such as the 260 Rem to shoot tight little groups is not an overly difficult thing to do. In fact some rifles that are really quite poor in machining quality will still shoot very tight groups with rounds of this class.

In a rifle chambered for say a 223 Rem, its actually quite difficult to build a rifle that is not extremely accurate if you use quality componants.

THis is not the case once case head size increases to that of the belted magnum. Machining has to be much better quality and everything needs to be in perfect axial alignment or fliers will become present. This is because the increased stess on the rifle system will magnify any flaws in the machining.

When you go up to a Lapua or big Wby class case head, this is magnified significantly more. Perfection is the only option to get a fine shooting rifle in these calibers.

Now please do not take this as me saying that I fly through my smaller caliber rifles because there is no reason to pay attention to detail in the rifle build. That is hardly the case, every one of my rifles is built the exact same way as are all the rifles from other accuracy minded smiths.

But I will say as the size of the chambering increases, so does the stress on the receiver and rifle system as a whole. As such the need for perfect squareness and perfect axial alignment is extremely critical. Perhaps the most important is the bolt, receiver relationship since this is the footprint which all performance is started from in a rifle. If the round is not launched off a square platform, it will be variable from the start, read this as "fliers".

As such, it is for this reason why I feel the Wby MkV, inspite of its strenghts, is at a disadvantage compared to other receivers with all locking lugs in a single plane which can be easily machined and lapped into 100% square contact.

Unfortunately my friend, I have built enough rifles on Wby and Rem 700 receivers to have a pretty decent idea how each will work.

Again I will admit that many rifles built on the Wby MkV receivers are great shooters. In fact I will say most of them are great shooting rifles. STill, there are those very few that simply will not, no matter how much tuning and machining and load tweaking you do will get fine consistancy, that being in my mind, sub 1/2 moa accuracy.

It is not common but it certainly does happen. Every top smith I have talked with has stated this same experience.

In comparision, I have yet to ever have a Rem 700 not meet or beat my 1/2 moa accuracy requirement and I have built several times many more rifles on the Rem 700 then the Wby MkV receiver.

Why is this the case, All I can guess it that its the bolt locking lug as that is about the only thing that I can not easily true and accurize. Everything else is easily trued in the same fashion as the Rem 700. Other then that the only other thing it could be is the barrel shank dimension.

So while I know you really want me to tell you that we can certainly use the Wby MkV receiver and get extreme performance from it, for my customers wanting my honest opinion on what receivers offer the highest possibilities of producing a true sub 1/2 moa rifle, the Wby MkV will not now or will it ever make my short list of recommended receivers.

Even though most will do this, there are those that will not.

Good Shooting!!

Kirby Allen(50)

 

[Hired Gun]

Okay, just a couple more. For the bolt fit, can anything be done like on the 700 to tighten it up? Sleeves, Borden like bumps that tighten it up when the bolt is shut?

And then as to getting the all important 100% contact. Isn't it just a matter of time and using more aggressive compound until the goal is acheived? No worries of headspace issue as that is corrected when the barrel is mounted.

One other thing that has come up and I wish to explore is you mentioned fitting the barrel face within .005 of the bolt nose. Why not go a step farter and put a, oh say a 30 degree bevel on it and a matching 30degree chamfer in the barrel and going for a slight crush fit to center and stabilze things even more?

 

[Crane]

How about the extractor issue, can a Sako type or something similiar be fitted to the Mark V as they are in the 700?

 

[AJ300MAG]

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One other thing that has come up and I wish to explore is you mentioned fitting the barrel face within .005 of the bolt nose. Why not go a step farter and put a, oh say a 30 degree bevel on it and a matching 30degree chamfer in the barrel and going for a slight crush fit to center and stabilze things even more?

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It's been proven with benchrest rifles that if the bolt has any contact with the barrel it destroys accuracy.

 

[alremkin]

I just re-read Lilja's article on why the Remington 700 action shouldn't be used for large cases like the 378 Weathby, 338 Lapua, or 416 Rigby. Lilja says that the Remington action is too weak and short so it's only able to be used for single shots. I can't see that you're more concerned about alignment, but how do you reconcile this with Lilja?

 

[getsmart]

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Again I will admit that many rifles built on the Wby MkV receivers are great shooters. In fact I will say most of them are great shooting rifles. STill, there are those very few that simply will not, no matter how much tuning and machining and load tweaking you do will get fine consistancy, that being in my mind, sub 1/2 moa accuracy.

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Kirby, Can you tell say on a factory Mark V how good the lug contact is before you work on them? Perhaps by how they shoot prior to accurizing with factory barrel?

Or do you find this out after you accurize and realize the only 7 lugs contact evenly?

 

[Fiftydriver]

Hired Gun,

Yes, I suspect you could fit the Wby Bolt with sleeves and tighten up the bolt to receiver fit. With the fluted bolt I would have to take some measurements comparing the bolt baring surfaces and the receivers mating surfaces and see that it would work but I do not see why not.

Depending on how far the floating lugs are off their mating surfaces will determine if they can be lapped into contact. Yes you can lap them into contact but remember these are very hard surfaces and if you have to lap away to much area, you will be lapping for a long time.

All quality built rifles with a bolt nose recess in the the barrel design will have a bevel in the barrel recess and on the outside of the bolt nose. The problem is having the bolt contact the barrel. If you want some serious consistancy issues, have the bolt contact the barrel. Strange things begin to happen when there is contact or even something compressed between the bolt and barrel. It is critical that these two DO NOT solidly touch in any way.

If your chamber is in axial alignment and your bolt and receiver threads are in axial alignment and the locking lug surfaces are square, everything works great.

Kirby Allen(50)

 

[Fiftydriver]

Crane,

No its not practical to machine a Wby MkV for a Sako or Badger Ord extractor. I had a 338 Kahn that I built on a Wby MkV for a customer that had extractor issues so I tried to figure out a way to fit the bolt with either of these two aftermarket extractors. With the positioning of the bolt lugs this is not practical.

Kirby Allen(50)

 

[Fiftydriver]

Alremkin,

I believe, and I am not Speaking for Dan on this but I believe that when he says the Rem 700 is to short and weak he is referring to the use of heavy, long barrel generally used with these chamberings for long range rifles.

In my talking with Dan and explaining that with the real heavy, long barrels, that Barrel Bedding V-Blocks would be used with a 100% floated receiver that there would be no problem with chambering the Rem 700 for these large cased rounds.

Again, this is what I have gotten from talking with Dan and I suspect his concerns were with barrel weight and length causing receiver flexing. With a Rem 700 this is certainly an issue but it is just as much an issue with the Wby Mk V as well with really heavy long barrels.

In both cases I recommend a barrel no heavier then a #8 contour and no longer then 30". If a longer or heavier barrel is wanted, I recommend a custom receiver or the use of a Barrel Bedding V-Block system so that the barrel supports its own weight, not the receiver supporting the barrel weight.

The "short" comment is pertaining to the fact that as a repeater, the Rem 700 magazine window is not long enough to allow the 30-378, 338-378, 378, 416, 460 Wby, 416 Rigby class rounds to feed through the window. They can be machined longer but I do not recommend this either with tese large case head sized rounds.

I am saying that for this class of rounds you have to use the Rem 700 as a single shot only option. But for the 338 Lapua and all wildcats based on this case design, the Rem 700 works perfectly well as a repeater because of the shorter case length and OAL cartridge length.

Kirby Allen(50)

 

[Fiftydriver]

Getsmart,

On a new rifle is can be difficult at times to tell the amount of lug contact on a Wby receiver. But a used rifle is pretty easy to tell simply by looking at the locking lug surfaces on the bolt locking lugs.

Again, I have built some Wby rifles that shot very well with only 6 lugs baring evenly. I have also shot some that did not shoot well with this number of baring lugs and even more.

That is the reason for me to not recommend the Wby receivers for extreme accuracy rifle builds, There are just some receivers that will not shoot.

I want my customers to have the most for their money and thats why I do not recommend the Wby receivers for this type of rifle.

Kirby Allen(50)

 

[Coyboy]

Kirby, I have some questions about the realationship between the bolt nose and barrel recess on the 700.

How much clearance is necessary for the escaping gasses to flow around the bolt face and out the gas hole on a case rupture? If the tolerances in the fit are too tight could this cause a major action falure verses a ruptured case head? What have you found to be the clearances on a factory 700 barreled action?

Thanks for an interesting discussion. Jim