Consider the source(s)!!

From a design standpoint, the FN/M70/M1903/M1917 bolt lug placement (at the front of the bolt head) is demonstrably weaker than the 1898 Mauser's placement (slightly further back). The shear strength of the forward-placed lugs is slightly compromised, as shown by the slanted shear surface of the break. This comparative weakness isn't present in the 98 Mauser, M700 Remington and others, with their lugs placed slightly further to the rear and thus better-supported by the major diameter of the bolt body.

On the other site, Fighthard's (gunnery sergeant, HAH!) comment about the relative problems with Rem 700 vs M70 is basically ignorance and BS IMO. I've seen lots of failures with Remington but NEVER with their bolt lugs! OTOH I've also seen M70s and M1903s with their lugs broken off completely, just as this one was.

Like the man said, you gotta consider the source(s)!
Regards, Joe

Clearly it is crystallized metal from being too hard/brittle; if we assume the bolts are made from 4140; they didn't draw it back enough after hardening. If made from 8620, they put way too much carbon in it, too deep, and didn't stress relieve correctly. In this case, any correctly heat treated bolt would not have done this; they just keep on shooting and the metal, usually the receiver, stretches. Never catastrophically breaks like this. Even if both lugs give way, you still have the bolt handle as a safety lug; glad that didn't happen. I am sure FN will never reveal the results of their investigation, but they should do some serious checking of their QA/QC program. True, the M70 design is not ideal, but this should never have happened. Ever.

quote:

Originally posted by J.D.Steele:
From a design standpoint, the FN/M70/M1903/M1917 bolt lug placement (at the front of the bolt head) is demonstrably weaker than the 1898 Mauser's placement (slightly further back). The shear strength of the forward-placed lugs is slightly compromised, as shown by the slanted shear surface of the break. This comparative weakness isn't present in the 98 Mauser, M700 Remington and others, with their lugs placed slightly further to the rear and thus better-supported by the major diameter of the bolt body.

On the other site, Fighthard's (gunnery sergeant, HAH!) comment about the relative problems with Rem 700 vs M70 is basically ignorance and BS IMO. I've seen lots of failures with Remington but NEVER with their bolt lugs! OTOH I've also seen M70s and M1903s with their lugs broken off completely, just as this one was.

Like the man said, you gotta consider the source(s)!
Regards, Joe

Fighthard's post of 12/23 on the other site gave me plenty to assess his crediblity as nil.
most of his analysis simply fails to acknowledge the optical illusion created by an image of a re-entrant face.
even IF #4 was an inclusion it was not at a site that I would consider initated failure from the forces involved, or contributed significantly to the failure.

as for the crack theories.........DUH .
nothing there indicates progressive crack propagation to me..........only catastrophic shear failure of a hardened steel.

I don't use reloader or a WSM but the interesting post was the pressure calcs for R17 & R22 & the reload manual printed data referring to R17.

it doesn't seem like the other thread ever got to the bottom of that.
you sure would hope that the shooter checked that "minor" detail before continuing when he got his rifle back.

A bunch of seriously overpressure rounds would explain an eventual shear failure........as might a bad enough single overpressure round.

One takes the shooter's statements at face value.

Catastrophic shear failures look exactly the same whether the material is out of spec & too brittle or the material is in-spec & force is excessive.

Post event metallurgical analysis clarifies which scenario existed.

Sadly, the CS claim response is pretty standard in business these days, its pretty typical to see a dollar value up to which there is a 'no questions asked' replacement approach & above that a 1st response brush-off as your fault, which a percentage of claimants accept ( good business they usually pay for the part & labour )..........and serious claim assessment & response only if you continue to pursue the claim.
The more money that's involved in the claim, the more dithering there is in the processing, when you do persevere with the claim.

$300 or so claim on a $5000 item, ....HAH......wait till you see what happens with a genuine $3M claim........been in those shoes????

I've never seen that before, and i would love to see an honest report of what the cause was.

How about an entire receiver snapping?

http://www.snipershide.com/for...wflat&Number=2419869

quote:

Originally posted by J.D.Steele:
(gunnery sergeant, HAH!)...
Like the man said, you gotta consider the source(s)!
Regards, Joe

thats the "karma" rating. not a military rank.. we have two here.. new member and one of us .. make a certain number of posts in a certain number of days, and you are auto rated.. thats all it means.. don't nitpick

I would very much like to see the rear surfaces on those FN lugs. I would be willing to bet that that right lug was making most if not all of the contact. THERE ARE REASONS FOR LAPPING THE LUGS other than better accuracy.

quote:

Originally posted by J.D.Steele:
From a design standpoint, the FN/M70/M1903/M1917 bolt lug placement (at the front of the bolt head) is demonstrably weaker than the 1898 Mauser's placement (slightly further back). The shear strength of the forward-placed lugs is slightly compromised, as shown by the slanted shear surface of the break. This comparative weakness isn't present in the 98 Mauser, M700 Remington and others, with their lugs placed slightly further to the rear and thus better-supported by the major diameter of the bolt body.

care to elaborate why M70 lugs would be less supported by the bolts major dia. compared to M98?




M98 lugs have an slanted shear surface just like the M70....
So much for your theory on M98 lugs being better supported/not having the same claimed "comparative weakness" of the M70.

I very carefully used weasel words like 'better-supported' and similar. I didn't say that the Mauser lugs WOULDN'T or COULDN'T shear at a slant, I said the shearing itself was less likely.

If you truly question my opinion and are not merely expressing your own contrariness and personal dislike for me, I suggest that you have your own engineer conduct an analysis of the relative design strengths. We will await his results.

Until then, that's my opinion and I'm stickin' to it.
Regards, Joe

I would just like to know what all these bolt and reciever failures were caused by.

People learn by failures. I dont mind learning from someone elses.

Cheers, John

My personal favorite was the one that said the factory could tell if you were shooting factory or handloaded ammo by the residue in the barrel!

Lug shear and bearing area is actually smaller on a 98 as compared to a P64 M70.

And in looking at the grain structure of the bolt it appears to be through hardened but again you'll never know what is wrong until some tests are made on the steel

quote:

Originally posted by BECoole:
My personal favorite was the one that said the factory could tell if you were shooting factory or handloaded ammo by the residue in the barrel!

A customer of mine won a law suit against Olin many years ago over that exact claim.

quote:

Originally posted by Westpac:

quote:

Originally posted by BECoole:
My personal favorite was the one that said the factory could tell if you were shooting factory or handloaded ammo by the residue in the barrel!

A customer of mine won a law suit against Olin many years ago over that exact claim.

I was gonna say maybe the guy forgot to stop typing.

Should have read" My personal favorite was the one that said the factory could tell if you were shooting factory or handloaded ammo by the residue in the barrel!

I would have loved to see them explain that one though

quote:

Originally posted by J.D.Steele:
I very carefully used weasel words like 'better-supported' and similar. I didn't say that the Mauser lugs WOULDN'T or COULDN'T shear at a slant, I said the shearing itself was less likely.

Be kind enough to quote yourself where you actually said "shearing was less likely in M98",.....I sure as hell cant find it.

quote:

The shear strength of the forward-placed lugs is slightly compromised, as shown by the slanted shear surface of the break. This comparative weakness isn't present in the 98 Mauser

you clearly implied that slanted shear surfaces are due to location of the M70 lugs, you then go on to say that such comparative weakness does not exist in M98.
Which suggests that M98 lugs should not shear at angle like M70,.. No?

quote:

Originally posted by J.D.Steele
If you truly question my opinion and are not merely expressing your own contrariness and personal dislike for me, I suggest that you have your own engineer conduct an analysis of the relative design strengths. We will await his results.
Until then, that's my opinion and I'm stickin' to it.

So is it just pure opinion on your part, you have no existing sound engineering anlysis results to support what you claim?

How about something of valuable imperical substance, rather than your typical shoddy annecdotal hearsay approach.

Q./...care to elaborate why M70 lugs would be less supported by the bolts major dia. compared to M98?

This seems to be a repeat of the snipershide threads, unfortunately. Does anyone actually know what can be learned from these failures? They look like brittle failures to me. If they were fatigue cracks then there would be some plastic deformation as the failures became catastrophic.

I was also thinking that maybe the color change could be from cleaning solvents and oil seeping into a developing crack, and the color changes where the fresh break is.

Trax, it's pretty obvious that you don't like me so why don't you put me on your 'ignore' list?

Run the calcs (if you know how), you'll find out the relative strengths.

And for a good example of the strength, or rather weakness, of the M70 action, I suggest you consult Ackley's Handbook. Since you like pictures so much, maybe Ackley's M70-blowup photo will put some new colors in your paint box.
Regards, Joe

quote:

Originally posted by jpl:

I was also thinking that maybe the color change could be from cleaning solvents and oil seeping into a developing crack, and the color changes where the fresh break is.

That is most likely the dramatic difference in color. Usually on a fractured part that is case hardened the "color" difference is minor. The grain difference is major. On this part I see no difference in grain structure but the part in not in front of me either. It appears to be a through hardened part. and the most likely cause was a poor heat treat job. Yes an over loaded cartridge can do is as well but it would have to a very big mistake in the loading process like a double charge

Trax would do well to go park his butt at Varmintal's a while.
But then again he may cherry pick stuff there he does not take time to understand and paste it here.