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

[Fiftydriver]

I have had several conversations lately about why I feel the Rem 700 can be used successfully to build rifles chamebred for such rounds as the 338 Lapua and large Wby case heads and any wildcats based on this size case head.

Many find it hard to believe that the two lugs on the Rem 700 could possibly compare to the strength of the 9 lugs on the Wby MkV.

So I decided to actually measure the baring surface and shear area of the lugs on these two bolts and see how actual rifles compare to each other.

As far as baring surface, the area of the bolt locking lug that actually contacts the Receiver locking lug recesses, here is what I came up with:

Wby Mk V................0.120 square inch
Rem 700.................0.138 square inch

As far as shear area, the area that contacts the bolt lug to the body of the bolt its self as as follows:

Wby Mk V................0.361 square inch
Rem 700.................0.387 square inch

Not these are numbers taking into account 100% lug contact area which with the Rem 700 is relatively easy to accomplish. With the Wby receiver, this can at times be impossible to get and generally the best you can get is 7 or 8 of the 9 lugs baring solidly.

Also looking and measuring the receiver locking lug recess area, It appears that they are basically equal in this area.

So, for those that say the Rem 700 should not be used with these rounds. I am just curious to the basis of your recommendations.

Please keep in mind that I feel only Chrome moly Rem 700 receivers should be used for such conversions as the Chrome moly is harder and resists bolt lug recess set back much better then stainless receivers. That said, I have used Stainless receivers for personal testing and have witnessed no problems even using these receivers.

Just curious as to the different opinions on the subject out there.

Kirby Allen(50)

 

[budlight]

Without the scientific factory testing data, any of our inputs could only be guesses. The safety factor built into rifle bolt has to be phenomenal.

The bolt in neither of the guns I have personally seen failed. The first major rifle explosion I got to inspect was a Rem 700 300 win mag. The reloader had filled the cases with something like 4320 instead of the usual 4831. It blew the back of case off and shattered the stock all around the magazine. The forestock actually split and the lower part fell off. The shooter was unhurt. The case had to be pulled out with a needle nose and after a new stock; I would guess that it's probably in use today.

The second reloader failure had something to do with a 220 swift and purchasing the wrong diameter bullets. I'm not a 22 cal man so I didn't follow the whole story. Something about purchasing .223 or.224 bullets and the 220 swift uses something smaller. On the pull of the trigger. The guy got a right cheek full of hot brass and the same thing, the whole rear of the case had been blown off.

I've been more fortunate and only blown primers out and that has even included the new 30-378. You just end up pounding the bolt open and pulling the rest of that lots bullets.

I build and run Chevy race car motors. These super strong metals can take lots of shock. But it must cause micro fractures and with repeated times eventual failure.

My guess would be that multiple lugs or in the case of motors and transmissions multiple splines are always stronger than a few larger ones. But it's all a moot point because it might take something like black powder or pistol powder to actually be ably to make an explosion big enough to fail the bolt in either gun.

 

[goodgrouper]

Ahwile back, I read an article on this and I can't remember where it came from (PO ackley's books maybe or PS magazine??).

They took all the major brands actions of the time and tested the shear strength of the lugs and bursting point of the reciever/barrel. It was fascinating. THey came up with similiar conclusions to your measurements.

Also, one of the custom action places have a write up of some tests similiar to yours on their website. It may have been Nesika or Bat possibly. Been too long ago now to remember.

 

[Buffalobob]

I had a Mk V in 7mm and wanted to hunt some turkeys in Missouri so I got some FMJ bullets and some IMR4227 and prepared some reduced loads according to the manual. They were fine but then I decided I wanted just a little more speed so I add more powder than the manual recommended. The results were extreme. Being somewhat stupid, I fired two more rounds before deciding that something was definitely wrong. Each time flame came out of the three ports in the bolt for about six or more inches. The cases had partial head separation and primer meltdown. The gun was fine.

I think you might need to look at the Mk V as a system that includes both pressure relief holes in the bolt , freebore, as well as locking lugs rather than a locking lug only issue. The Rem has a pressure relief hole in the receiver as opposed to the bolt.

Maybe it is just my impression from the finish of the metal but I thought the steel itself was stronger in the Mk V. Probably just my imagination.


Going to what Budlight says, the question may be related to elasticity and lug flex as the nine smaller lugs flex and progressively coming into bearing as opposed to a catastrophic failure of a large lug. It would be possible to shear two or three lugs and for the others to still hold. On a Rem lug once you get a stress fracture running you will be in for catastrophic failure. Just my opinion of a possible scenario but I have no science to back it up.

The MK V bolt shroud worked as advertised with nothing coming back into my face. My trigger hand and wrist got lots of stuff splattered onto it. I have gotten stuff into my face with the Rem 700. What that stuff was is most likely just gun oil from th firing pin cavity mixed with burning powder

One way to think about it is like wheels and hubs. For a little Civic you can get by with with four but as you get up into a large pickup you will have six lugs. Of course in this case you "bearing surface and shear area" are increasing which is not the case with the Mk V and Rem where the area decreses witih the number of lugs.

I have separated a lot of case heads in the Ruger falling block and it holds well and is no trouble except that I think with a lot of it my action has gotten loose but I don't know how to measure that.

I have an old Mossberg in 225 Win that was given to me because the owner could not get it to shoot. It only has one lug!!!!! I actually killed a deer with it but it still doesn't shoot well.

I have no real opinion on whether one is stronger than the other but I do defend that the Mk V held when I did something extremely stupid - three times.


Budlight

What the guy with the 220 may have done is get some 227 bullets (228 Ackly - he built it to get around the prohibition of using a 224 caliber on deer) and loaded them up. They are there on the display case right next to the 224s and come in 70 gr just like the 224s. Give you one guess why I know this.

 

[sniper2]

Two pieces of steel are stronger than 9 smaller divided lugs if they are of the same material period. We have tried several locking lugs on wbys and are yet to find one that all nine lugs were bearing.In their defense the port holes and the free bore in the wbys are their real safety factor.
The three locking lug system found on some of the older actions ('98) I consider among the strongest.

 

[sambo3006]

In response to Buffalo Bob mentioning that he wanted to hunt turkeys in Missouri with his 7mm Weatherby, it is most definitely NOT legal to use a rifle of any kind for turkeys in Missouri. Maybe this was years ago when game laws were different(I don't know). I'm not trying to bash anybody, I just don't want to see someone get written up for a game violation.

 

[Hired Gun]

I'll try to stay on task here but I have lots of thoughts pertaining to the 700 verses Mark V decision.

Given the simple math, I agree that on the surface the shear area of the two are comparable but from my racing background I two have observed that many small lugs, splines or threads are always stronger than a couple big ones. I can't explain why but it is a proven fact. Might be something to due with the fact that a fracture of one can easily travel through the mass of any one but is harder to initiate fracture through all of them.

Accuracy potential wise, I personally believe as Dan Lilja and others have stated that a bolt head supported on three sides is more stable at the moment of firing than a two lug design. Furthermore the success of a two lug design is largely dependant of achieving 100 percent lug contact to help stabilize the bolt and eliminate flex. The two lug design is also highly dependant on the fit of the bolt in the raceway. That is why the Remington's show marked improvement from the use of bolt sleeves and oversize bolt bodies to further help stabilize the two lug design. A bolt head bolt such as the Sako, Weatherby and the Geske action is supported on three sides. Dan Lilja states, "Gerry (Geske) also believes that three lugs provide a more stable bolt face. One less subject to vibrational effects than a two lug design." The Weatherby and the Geske action strengths and stabilities are further enhanced by the lack of bolt lug raceways and their full diameter bolt bodies. The Mark 5 Bolt body is .841" in diameter where as the 700 is only about .705" or so. That's more than an 1/8" bigger in a world that is measuring the differences in the hundredths and thousandths column. This massive shaft behind the bolt face has got to help support the bolt face from flexing.

It was also brought up that the recoil lug if properly fitted help support the barrel on a 700. I submit that upon firing even if properly fitted and super thick/strong etc it still imparts a shock to the barrel action joint. The Mark V has the recoil lug built into the bottom of the action so upon firing it imparts no shock to the barrel action joint.

The Mark V action comes with a trigger that with only a spring mod or change will allow it to be adjusted well under 1 pound where the use of a 700 action is going to need an aftermarket trigger to achieve the same level of quality in trigger pull.

To sum up I believe that a production Mark 5 action is a superior design in both strength and accuracy potential when compared to a Remington.

 

[Jon A]

[ QUOTE ]
but from my racing background I two have observed that many small lugs, splines or threads are always stronger than a couple big ones. I can't explain why but it is a proven fact.

[/ QUOTE ]
As a Stress Analysis Engineer, I'd like to review these "proven facts" as I've never heard of them. Many things such as R&P's, Tranny gears, etc, don't leave all else equal for a proper comparison. There is something to the failsafe design concept--make it strong enough so it'll still hold after one has failed and this would favor the 9 lug design as losing one of them loses you a smaller percentage of your total strength. But, most here would consider getting to that point "too late." They're interested in preventing lug setback, etc, well below the failure point where the above philosophy hasn't kicked in yet.
[ QUOTE ]
I personally believe as Dan Lilja and others have stated that a bolt head supported on three sides is more stable at the moment of firing than a two lug design. Furthermore the success of a two lug design is largely dependant of achieving 100 percent lug contact to help stabilize the bolt and eliminate flex. The two lug design is also highly dependant on the fit of the bolt in the raceway. That is why the Remington's show marked improvement from the use of bolt sleeves and oversize bolt bodies to further help stabilize the two lug design. A bolt head bolt such as the Sako, Weatherby and the Geske action is supported on three sides. Dan Lilja states, "Gerry (Geske) also believes that three lugs provide a more stable bolt face. One less subject to vibrational effects than a two lug design."

[/ QUOTE ]
That's why all you losers should buy A-Bolts! /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

 

[SeniorSendero]

Weatherby designed his action such that in the event of a case head failure, or any failure, everything will blow out the front. A worse case scenario was a fast powder in a magnum case with a barrel obstruction. Everything blew out the front with only a barrel bulge. The case head seperated with gas blowing out the ports in the bolt. No failure in the receiver.

I have seen a case head rupture in a Savage recently firsthand. It was a F prefix SN with controlled round feed. The entire receiver banana peeled away from the case case head rupture and blew pieces everywhere with dust in the air from the disintegrated Mcmillan A5 stock. The bolt had the controlled round feed area which propelled the bolt to the right and hit the shooter in the head immediately to his right, needing several stiches. Less than 50% of the gun was recovered, but what is left is very disconcerting as to how thin the reciever is in the area surrounding the bolt lugs (under 1/8" of metal). I'm not sure as to how thick the reciever is on a Remmy action around the bolt lugs though. I have read recently by Kirby that Savage recievers are not ducumented as strong and reliable, and I believe him 100%. This shooter now has a Weatherby Accumark for his birthday/Christmas present, but would not hesitate to have a custom rifle built by one of the fine gunsmiths on this forum.

Ronnie

 

[Fiftydriver]

Buffalobob,

The Rem 700 bolt does have a gas relief hole on the bottom of the bolt between the locking lugs.

It has been proven time and again that safety lugs such as those on the Mauser 98s are basically useless unless they are fitted to bare evenly with the main bolt locking lugs. The reason is that once a bolt lug fails to this point and gains rearward momentum, no additional lugs will stop this motion unless they are fitted to bare and work with the main lugs.

In my opinion, a floating lug on a Wby bolt is a waste of steel as it offers little to the strength of the receiver in my opinion.

Kirby Allen(50)

 

[Fiftydriver]

Hired Gun,

In theory a three bolt receiver may be more accurate then a two lug but it is interesting to me that the current world holder at 1000 yards used a Nesika Bay receiver, unless that group has been beaten since that time.

That receiver is a two lug receiver.

My point is simply look at the receivers that are used by the top accuracy shooters in the world and I suspect you will not see the Wby MkV receiver making up even 10% of the receivers used. My question is why is that?

Kirby Allen(50)

 

[Hired Gun]

Jon A
[ QUOTE ]
"As a Stress Analysis Engineer, I'd like to review these "proven facts" as I've never heard of them. Many things such as R&P's, Tranny gears, etc, don't leave all else equal for a proper comparison. There is something to the failsafe design concept--make it strong enough so it'll still hold after one has failed and this would favor the 9 lug design as losing one of them loses you a smaller percentage of your total strength. But, most here would consider getting to that point "too late." They're interested in preventing lug setback, etc, well below the failure point where the above philosophy hasn't kicked in yet"

[/ QUOTE ]

Respectfully I submit the following.
I never mentioned R&P or tranny gears as they are not a valid comparison. I mentioned lugs splines and threads. They are a valid comparison and the gross strength is directly related to the amount of load they will tolerate before suffering deformation or if you will, setback.

Now I direct to you as the most qualified here so far to explain the following and let us know if they are indeed facts and the philosophy is sound.

*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?

This means to me that fine threads allow a higher tensile or pull load before deformation and eventual failure. Why is this not a valid comparison?

I'm no engineer or gunsmith but I am a critical thinker that is more than a little mechanically inclined being a welder fabricator and millwright for most of my career. I build with my hands engineered designs as well as my own with equal success. I still stand by the following:
*Short stubby lugs resist deformation better than big ones.
*For the same shear area the one with the many small lugs should have a greater capacity than one with two big ones.

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.

As a stress analysis engineer this explanation should be elementary.

 

[Fiftydriver]

SeniorSendero,

I would agree that the design of the Wby is such that it is designed to release huge amounts of gas quickly in the event of a total case head failure.

That said, the design of the breech and bolt also allow this total case head seperation to happen because they have to be fitted with a certain amount of clearance between the bolt nose and barrel for the extractor to operate correctly.

With a Rem 700 this is not the case, I and most top gunsmiths machine the barrel bolt nose recess to have a total of 0.005" clearance between the trued bolt nose and the barrel bolt nose recess, thats 0.0025" on all sides. Also, the depth of the bolt nose recess is machined for only 0.005" clearance between the bolt nose and the barrel.

It is for this reason that it is almost impossible to cause a case head failure in a properly fitted Rem 700 using appropriate burn rate powders for the case and bullet used.

I witnessed one instance with a Rem XP-100 handgun chambered in 223 Rem that the owner got some powder mixed up on the load bench and instead of using the proper load of Win 748 under the 55 gr Ballistic Tip, it was later found out that the powder in the hopper was actually Alliant 2400. Both ball powders of similiar look at first glance but dramatically differnet burn rates.

The load was 26.0 gr of the wrong powder and on the first shot the XP made some strange noises and smoked severely btu the only thing that was wrong was that the bolt would not move to open the action.

We had to actually pull the barrel to get the receiver open. The case head was basically welded to the Rem bolt face as was the case in the chamber. When the barrel was removed the case was pulled apart at the case head but it had not seperated on the shot.

The only reason why was because it was a custom chambered barrel that was tight speced and did not allow the case to stretch enough to seperate on firing.

The receiver was sent ultrasonic checked for cracks and after rebuilding and rebarreled was put back to use chambered in 22-250 AI. Still in use today and shooting 1/2" groups.

I guess my point really is not what receiver will survive the most extreme cases of case failure. Both receivers are designed to protect the shooter and control escaping gases very well.

My question is why is the Wby MkV preceived as so much superior to the Rem 700 in strength for use with common sense top level loadings. As far as I know all modern receivers are proof tested at twice the PSI levels that they are regulated to by the chamberings used in the rifles. If anyone is loading to this point or even remoately close to this point they need their head examined.

My point is that for normal use with top safe loads, I see no way that one can say the Wby MkV is vastly superior to the Rem 700 in strength or consistancy.

As far as the Savage receivers are concerned. In my opinion, the weakest link in this rifle is the barrel lock nut ring which I have researched and found several instances were this lock ring split, and allowed the barrel to work loose slightly and upon further firing the headspace had increased enough to cause total case head failure. I would suspect this may be the case with the instance you post about, sounds very similiar to the instances I have read about.

Once that lock ring splits or loosens, nothing keeps the barrel from turning in the receiver. In only one or two firings the rifle will be totally destroyed.

One major reason for this, if you can believe it is over tightening of the barrel lock nut which stresses this thin metal.

Again, once the headspace increases to a certain point, case head failure is very likely.

As such, on all my rifles built on the Savage receivers, all barrels are fitted in the same fashion as the Rem 700 with no barrel lock nut present. Not only does it look much better but it vastly improves the strength of the barrel receiver engagement.

My comments about the Savage receivers not being strong was in response to a question about chambering my 7mm Allen Mag in this receiver and my comment was that I had not tested the Savage receiver or studied any tests of this receiver using a case head of this size and as such would not recommend using this receiver for my 7mm AM until the research could be done.

I have however tested the Savage receiver fully using my 270 AM loaded to some very serious levels and have encountered no problems in any way.

Kirby Allen(50)

 

[Fiftydriver]

Hired gun,

Not to get into your conversation with Jon A but in my opinion, as long as the receiver is built perfectly true and square, you will see no more vibration in a two lug then a three lug.

To that point, which is more stabile, two perfectly 100% baring lugs on each side of a bolt, or two out of three lugs baring on a three lug bolt?

Or, in the case of the Wby, what happens if you have two of the three rows of lugs baring but in one row, only one of the three lugs bare.

Is it not common sense that that one lug baring on that third of the bolt body will flex dramatically more then the other two thirds of the bolt? As such, allowing the bolt body to shift laterally?

THis is my point. If all nine lugs bare evenly it is a great system. In a three lug system such as the Sako or Browning, when you accurize them and get 100% lug contact, I agree they are superior designs, BUT, the Wby receiver is nearly impossible to get all nine lugs to bare evenly.

My point to this is, one third of the locking lug columns will always compress or flex more then the others unless all columns have an equal number of locking lugs baring evenly.

This would mean that either one in each column would have to bare with all others floating, or Two in each column would have to bare in each column or all three would have to bare, not only that but they would also have to be in the same plain as well or there will be some bolt head flexing.

So to put it simply, I agree that a three bolt design with all lug baring surface on the same plane is a superior design to the two bolt design, but that is simply because this bolt design is easy to true so that you have 100% contact.

The Wby is EXTREMELY difficult to get this in and as such, this is the point to my original post.

In talking with Dan personally many times on this subject, he favors the three lug on the same plane design, not the Wby design with 9 lugs on three seperat planes.

Good Shooting, good conversation as well. Good points all around.

Kirby Allen(50)