Thanks in advance.

Reed

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RAB

Somemore interesting numbers.

I measured the lugs and receiver of a Vz24 I had and calculated the load bearing area of the lugs. I then performed a some stress calculations.

Materials:
SAE 4140 (modern actions)
Yield Strength: 145,000 psi
Tensile Strength: 161,500 psi
Endurance Limit: 72,500 psi

SAE 1340 (old actions this is ordnance steel)
Yield Strength: 120,000 psi
Tensile Strength: 140,000 psi
Endurance Limit: 60,000 psi

Thrust forces of 416 Rigby
@ a chamber pressure of 40,000 psi = 6240 lbs
@ a chamber pressure of 60,000 psi = 9332 lbs

Recoil lug actual contact are (85% contact) = 0.128 in^2 (considering both lugs)
= 0.0638 in^2 (considering only one lug)

Contact stress due to thrust force:

Lapped action (both lugs bearing 85% contact)

@ 40,000 psi chamber pressure the contact stress is = 48,750 psi

@ 60,000 psi chamber pressure the contact stess is = 72,906 psi

Unlapped action (only one lug bearing load)

@ 40,000 psi chamber pressure the contact stress is = 97,805 psi

@ 60,000 psi chamber pressure the contact stress is = 146,270 psi.

Even the old mauser actions should not have a terribly difficult time with the 60,000 psi chamber pressure loading of a 416 Rigby. The stress is above the endurance limit but far below the yield point! If a 500 Jeffery is setting back it's bolt I would say either the steel is far below specification or the lugs are not properly lapped therefore distributing load like the second set of stress calculations in which the contat stress (146,270 psi) is above the tensile strength of the older material.

Alf, I would definitely make sure that the lugs in your 500 Jeffery are lapped well so that both lugs are bearing evenly.

Todd E

I slept through most of the materials classes, so you have to tell me what endurance limit is. Are you talking about fatigue?

Bill

quote:

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Originally posted by Atkinson:

I am one of those who has never blown a rifle in 50 years plus, and loaded literally millions of rounds.

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A single million is a lot. Multiple millions is a whole lot of rifle ammo for one guy. If you shoot 50 rounds a day, every day for 50 years straight you will still be well short of a million rounds fired.

When I was doing a lot of shotgunning I was shooting about 10 - 15,000 rounds per year. You have to work really hard to do that much shooting. If I kept up that pace for 75 years I could have a million rounds under my belt. That's with a shotgun though.

A million rounds with a rifle really is a whole lot.

Like a moth to a flame - I couldn't stay out of this thread.

Like Ray, I often take a case to the first indication of the ejector mark or the slight shiny mark casued by the ejector slot on M70s.

Here is a bet I will make with you.

Take a rifle like a 270 and use IMR4350 and the 150 grain bullet.

Now start with the starting load in one of the modern manuals and then keep going up a grain at a time and keep going. Provided you don't use a mallet or ramrod to assist extraction, I bet you won't get into trouble.

About the worse case scenarios will be that you might put a burn mark on the bolt face and you might get a little bit of smoke back through the action. This seems to happen with Rem 700s but not M70s.

Now the first sign of an ejector mark will only be a grain up from when it was not there.

With the soft brass we have today, especially the Remington bulk brass from Huntingtons, a load that is only a grain below the ejector mark, can cause problems with barrel fouling conditions, especially in calibers with big case capacity for the bore. No you won't blow yourself up, but you may loosen a primer pocket, have difficult extraction, none of which is needed in the field.

But Ray or I won't suffer from that inconvenience because we already know where the red line is

Mike

I did say

"If brass is soft and the caliber has a big case for the bore size (calibers like 7mm STW etc. OFTEN retain accuracy to higher pressure than rounds like the 375 H&H) and a very good barrel in a well bedded rifle"

often not always

Mike

The endurance limit is a threshold in certain metals (ferrous alloys and titanium are the most common) that established infinite fatigue life. In other words if you load a steel part in cyclic fatigue such that the stress is below the steels endurance limit it should last indefinitely.

That said, the endurance limits that I posted are theoretical (.5 of the Yield strength). In the real world with the endurance limit is typically lower than .5 * Yield strength.

Anyway, the point I was trying to make is that from a fatigue viewpoint there is no reason that a properly lapped action should set back the bolt even after several thousands rounds. The stress are below 50% of yield. A typical steel part's life will follow a 4 to 8 power of stress relationship. That is not well explained.

Example: Assume we have conducted experiments and determined the log S - log N curve for a steel component. We then test another design and generate a separate log S - log N curve for this second design. We then crunch numbers and determine that the log S - log N curve from design number 1 is defined by the equation X / stress ^4.

The log S - log N curve for the second design is defined by the equation
Y / stress ^8.

These are somewhat the extremes of good design practice with steel components. That is not to say that there are steel components which do not exhibit better or worse fatigue life.

Considering these equations it is easy to understand why with the relatively low stress of a properly lapped action why I say that there should be no set back until several thousand shots have been taken with a 60,000 psi chamber pressure loading. Also, remember that there is a time component to the stress here. It takes time for the component to comprehend that it has been stressed. This phenomena often manifests itself as follows. The tensile ulitmate strength may be 3 to 5 times the "normal" when the loads are applied in a few milliseconds. This is why seat belts do not tear apart in car accidents and also why you are not literally cut in half.

I did not post this to start anything. I just wanted to point out to Alf that there may be something else going on with his rifle. There are many assumptions being made with regard to the thrust force and also to the load distribution across the action. My calculations are an average at best. Again my purpose to raise a flag to Alf that maybe just maybe he has some other more serious problem.

Todd E

[This message has been edited by Todd E (edited 04-25-2002).]

I still agree with Longbob!

Rusty
We band of brothers!

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RAB

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

I refuse to let Ray be buried with "Sweet Thang", and that Mauser 404 Jeffery is a beauty ! We can divy up the rest!

Rusty
We band of brothers!

Not because I want to know the exact location.

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RAB

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

quote:

---

Originally posted by Atkinson:
Forrest,
Get a life, that was a tongue in cheek number.

---

I've got a pretty good life already, but thanks for the sage advice. I was trying to emphasize your awe-inspiring experience. You wrote "literally millions" so I thought you meant it. Any other numbers there you didn't really mean?

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Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com

I am wondering what a 404 Jeff would get as far as fps with a GS Custom HV. I see on they site they have a 320 grain HV for the 404. I also see they have a 330 grain HV for the 416, which they say will get 2,900 fps, Would the 404 jeff get around the same?, I just would like to be better informed and think the 404 with this bullet would make a very good all round set-up,Thanks,Kev

I am very pleased that many people on this site have been so helpful it has restore my faith that there are still some good men left.I was going to get a 404J, but things did not work out,had a hard time getting a action that I wanted. I then went to a dakota, as I heard they are good and they have been around awhile.I thought I could get a 404J in there long action,375H+H, but they told me it would not work.I got a hold of my smith, so happens he had a 375 H+H dakota 76 and a 404J round with him. He called me back and said he could get it in it,but would be alot of work and it may be a problem,not a good thing for a DGR. So I had to step up to a long mag action,416 Rigby. I then said if I have a 416 rigby for a 404J it will defeat the purpose to save the weight. The differents turns out to be 5 OZS. I said then I will go with a 416 Rigby as I am there any way and have a wider selection of bullets.I just got tried of running into problem after problem.The 416 Rigby dakota 76 will be 2,500$, the long 375H+H dakota 76 was 1,950$.So I am getting a 416 rigby, like the song saids you can"t always get what you want.I think it really does't matter either will get the job done. The game will not notice the differents,just wanted to tell my story.And now you can call me crazy, I will get this rifle and it will be under 8 pounds.I have never had a problem with recoil, but was advised by my smith to have it ported.It will not effect the FPS, Thanks,kev

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RAB

Good luck either way. I was hoping we had another 404 Jeffery shooter...

Reed