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UtahShotgunner
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Reged: 07/01/08
Posts: 40
Loc: PA
Testing a modified/weakened Mark X Action
      #303862 - 09/08/17 12:28 AM

Found a Mark X online that had been modified as 'Cutaway' display.
Purchased it for the remaining parts as the price was right.

Front ring and chamber has been machined.

Have been told many times that drilling scope mounting holes in the upper lug can weaken an action.
Or that opening the magazine well for longer rounds is dangerous.
Etc.

From reading materials written in the early 20th century at the apex of using the Mauser actions for custom rifles, I believe that the 98 is much more resistant to failure and stronger than many believe.

What I will be doing is firing a number of factory loads to see if they lead to any failure. If it is still together, I will move 'up' to the hot Turk ammo.

If there is no failure, I could load some rounds over maximum, but without a pressure gun I wouldn't know the failure point.

It is my suspicion that even if I reach the point of case failure, the action will withstand it, even with the top of the front ring milled away.


I have several 8mm pull offs with trashed bores.
Have at least a dozen milsurp bolts on hand, so should be able to find a combination that will have proper headspace.

Also have a couple hundred rounds of surplus 8x57 ammunition on hand. Including a couple boxes of Turk, which is reported to loaded rather hot.

A wooden fixture (block of wood) that would hold the stripped action and trigger could be screwed too would be simple.

Will set up the GoPro type cameras and add a long string.

Anyone want to guess the number of rounds until headspace becomes excessive or a case lets go?

From arrival to prepared for the 'test'.









Bolt stop, bottom metal and trigger removed. Trigger replaced with one from my parts box.



FN Milsurp Bolt





The only 8x57 headspace gauge I have is a 'Field'
(WWI KAR98a barrel)



Doesn't close on 'Field'!



Factory Ammo



Closes on factory ammo. (Notice I removed cocking piece and firing pin. Safety first!)
Will need to get a set of Go/No Go or make a field expedient gauge with a piece of brass and some tape.




I am not sure when I will be able to get to the range to do this. <br /]Posting on a forum creates some pressure to get it done. [/color">

Edited by UtahShotgunner (09/08/17 12:31 AM)


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Daryl_S
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Reged: 10/08/05
Posts: 16219
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Re: Testing a modified/weakened Mark X Action [Re: UtahShotgunner]
      #303863 - 09/08/17 01:38 AM

Certainly gives a large gas-vent.

--------------------
Daryl


"a rifle without hammers, is like a Spaniel without ears" Edward VII


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93x64mm
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Reged: 07/12/11
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Re: Testing a modified/weakened Mark X Action [Re: Daryl_S]
      #303869 - 09/08/17 06:23 AM

Can see the point of explaining things - but its still a criminal waste of a good action!

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UtahShotgunner
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Re: Testing a modified/weakened Mark X Action [Re: 93x64mm]
      #303872 - 09/08/17 06:57 AM

Quote:

Can see the point of explaining things - but its still a criminal waste of a good action!




I bought it like you see it.

Salvaged all of the usable parts. At least we will get some information.


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Huvius
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Re: Testing a modified/weakened Mark X Action [Re: 93x64mm]
      #303873 - 09/08/17 06:58 AM

Purely a guess here but I am thinking that it will digest any "normal" ammunition you put through it.
The back surface of the top bolt lug is still intact and short of a case failure (which I doubt will happen too), I'm not thinking it will blow.

--------------------
He who lives in the past is doomed to enjoy it.


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xausa
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Reged: 07/03/07
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Re: Testing a modified/weakened Mark X Action [Re: Huvius]
      #303875 - 09/08/17 08:01 AM

Quote:

Purely a guess here but I am thinking that it will digest any "normal" ammunition you put through it.
The back surface of the top bolt lug is still intact and short of a case failure (which I doubt will happen too), I'm not thinking it will blow.




I fail to see why a cartridge fired in a chamber with the top portion cut away would not "blow". How can someone expect a brass cartridge case to resist 50,000 pounds per square inch exerted by firing the cartridge. The principle on which the copper crusher system of chamber pressure measurement is based assumes that the cartridge case will give way and propel the piston which crushes the copper cylinder. The diameter of the piston is only a fraction of an inch, but the cartridge case ends up with a hole blown in it corresponding to the size of the hole bored in the chamber to accommodate it.

If you insist on firing this mutilated rifle, I suggest you use a long lanyard and tie the rifle down to a tire carcass.


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Huvius
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Re: Testing a modified/weakened Mark X Action [Re: xausa]
      #303876 - 09/08/17 08:49 AM

The cartridge will be completely encapsulated in the chamber - even the leading face of the bolt is in its recess when the action is in battery.
I am sure that the lesson of the cutaway is to show just how the bolt lug interfaces with the action. In that, it still is just as if the top of the receiver ring was still present.

--------------------
He who lives in the past is doomed to enjoy it.


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Daryl_S
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Re: Testing a modified/weakened Mark X Action [Re: Huvius]
      #303880 - 09/08/17 11:05 AM

Quote:

Purely a guess here but I am thinking that it will digest any "normal" ammunition you put through it.
The back surface of the top bolt lug is still intact and short of a case failure (which I doubt will happen too), I'm not thinking it will blow.




That was also my impression. There is not enough case outside the solid head portion of the case - not much different than most single shots.

Most bolt CF rifles have 1/10" exposed between the end of the chamber and the front of the bolt. This one appears no different.
The locking lugs appear engaged OK, as long as that top one is strong enough with the cut out of the receiver.

I think I might take it easy on loads, measuring carefully and to the ten-thousandths, to ensure the remaining top ring is not moving.

Initial testing would be without me holding onto the rifle, ie; proof testing with full power loads and as noted, careful & bloody accurate measuring.

I should also not, I am not qualified to say it is safe to shoot - so - beware, what I would try with this gun, might be pure craziness.


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UtahShotgunner
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Re: Testing a modified/weakened Mark X Action [Re: xausa]
      #303881 - 09/08/17 01:43 PM

Quote:

Quote:

Purely a guess here but I am thinking that it will digest any "normal" ammunition you put through it.
The back surface of the top bolt lug is still intact and short of a case failure (which I doubt will happen too), I'm not thinking it will blow.




I fail to see why a cartridge fired in a chamber with the top portion cut away would not "blow". How can someone expect a brass cartridge case to resist 50,000 pounds per square inch exerted by firing the cartridge. The principle on which the copper crusher system of chamber pressure measurement is based assumes that the cartridge case will give way and propel the piston which crushes the copper cylinder. The diameter of the piston is only a fraction of an inch, but the cartridge case ends up with a hole blown in it corresponding to the size of the hole bored in the chamber to accommodate it.

If you insist on firing this mutilated rifle, I suggest you use a long lanyard and tie the rifle down to a tire carcass.




Barrel has been replaced with an 8x57 barrel from a KAR98a.



Edited by UtahShotgunner (09/08/17 01:44 PM)


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UtahShotgunner
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Re: Testing a modified/weakened Mark X Action [Re: Daryl_S]
      #303882 - 09/08/17 01:46 PM

Quote:



Initial testing would be without me holding onto the rifle, ie; proof testing with full power loads and as noted, careful & bloody accurate measuring.






I am not going to shoot this from the shoulder.

Quote:

A wooden fixture (block of wood) that would hold the stripped action and trigger could be screwed too would be simple.

Will set up the GoPro type cameras and add a long string.




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Homer
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Reged: 07/04/09
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Loc: Canberra, Australia
Re: Testing a modified/weakened Mark X Action [Re: UtahShotgunner]
      #303885 - 09/08/17 06:03 PM

G'Day Fella's,

Utah Shotgunner, please don't take this as criticism but it has already been wrecked, I can't see the point in destroying it.

It could still be used for what it was intended for, as a physical example for Show and Tell (but only with Dummy ammo!), for how these things Load (the magazine), Feed, go into Battery, Fire, Unload and Eject ammo/fired cases.
Maybe you could donate it to your local Gun/Hunting Club, for this purpose?

I recently milled out the chamber area and then another area, a few inches down the barrel, of a shot out .30 cal barrel.
This was just to show visiting inexperienced shooters (primarily), how the cartridge (a Dummy one) fits in the chamber, and how to adjust bullet seating depth, etc.

Regards
Homer

--------------------
"Beware the Lolly Pop of Mediocrity,
Lick it Once and You Will Suck Forever"


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xausa
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Reged: 07/03/07
Posts: 1791
Loc: Tennessee, USA
Re: Testing a modified/weakened Mark X Action [Re: UtahShotgunner]
      #303899 - 09/08/17 09:06 PM

Quote:




Barrel has been replaced with an 8x57 barrel from a KAR98a.




That's what happens when you spend all your time looking at the photos and don't read the text carefully enough. Boy, is my face red!

I think the action will probably do fine. I have seen any number of rifles fitted with German claw mount bases dovetailed into the receiver ring, where the dovetail extended all the way through the receiver wall, exposing the bolt lug recess. Although those rifles would probably not stand up against modern proof loads, they have been in use in the hunting field for decades with no ill effects.

I would still use the lanyard, however.


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Lee440
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Reged: 06/01/06
Posts: 32
Loc: Texas
Re: Testing a modified/weakened Mark X Action [Re: xausa]
      #303907 - 10/08/17 12:32 AM

Good on Ya Utah! This will be a great test and I will be very interested to see how it goes. I am of the opinion that it will do fine. I have taken apart many surplus 98's that showed evidence that only one lug was engaged and there was no telling how many shots had been down the bore. Yours still has an undamaged bottom lug/recess. Years ago, when there was a bunch of old Chinese knock-off 98's coming in for next to nothing, I wanted to pick one up and test it to destruction, just to see what they would endure with their primitive metallurgy, but never got around to getting one. I suspect, even they would have surprised us. Looking forward to your report!

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UtahShotgunner
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Reged: 07/01/08
Posts: 40
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Re: Testing a modified/weakened Mark X Action [Re: Homer]
      #303908 - 10/08/17 12:44 AM

Quote:

G'Day Fella's,

Utah Shotgunner, please don't take this as criticism but it has already been wrecked, I can't see the point in destroying it.

It could still be used for what it was intended for, as a physical example for Show and Tell (but only with Dummy ammo!), for how these things Load (the magazine), Feed, go into Battery, Fire, Unload and Eject ammo/fired cases.
Maybe you could donate it to your local Gun/Hunting Club, for this purpose?


Regards
Homer




No worries Homer.

I bought four cutaways. This Mark X, Browning BAR, Rem 700 and a Ruger M77.
Listing the BAR and 700 for sale today. Will probably sell the M77 to a buddy that is a Ruger collector.

Might donate if I could, but gotta pay the bills. . .


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UtahShotgunner
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Reged: 07/01/08
Posts: 40
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Re: Testing a modified/weakened Mark X Action [Re: Lee440]
      #303909 - 10/08/17 12:47 AM

Quote:

Good on Ya Utah! This will be a great test and I will be very interested to see how it goes. I am of the opinion that it will do fine. I have taken apart many surplus 98's that showed evidence that only one lug was engaged and there was no telling how many shots had been down the bore. Yours still has an undamaged bottom lug/recess. Years ago, when there was a bunch of old Chinese knock-off 98's coming in for next to nothing, I wanted to pick one up and test it to destruction, just to see what they would endure with their primitive metallurgy, but never got around to getting one. I suspect, even they would have surprised us. Looking forward to your report!




Kind of wish it was a cheap milsurp as the Mark X is among the strongest (metallurgically) of the 98's made.

If that proves to be the case, I can put it back together and donate it as Homer suggested.


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Vladymere
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Reged: 11/08/15
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Re: Testing a modified/weakened Mark X Action [Re: UtahShotgunner]
      #303921 - 10/08/17 11:00 AM

UtahShotgunner,

I look forward to your testing.

A thought on your head space testing. My understanding when testing head space is that the bolt should be stripped of the striker group and the extractor so they will not impart any friction to the turning of the bolt. The bolt is then allowed to close on it's own without assistance.

I have read that "hot" Turk ammo was not loaded "hot" but loaded to German specs and then through improper storage the powder deteriorated causing "hot" loads.

The above is not meant as criticism.

Vlad


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mauserand9mm
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Posts: 711
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Re: Testing a modified/weakened Mark X Action [Re: Vladymere]
      #303924 - 10/08/17 01:29 PM

I think the results will be suprising.

Hatcher did some strength testing of Springfield rifles many years ago:

- He turned down the steel over the chamber in stages until it was 1/16" (1.5mm) thick and it withstood the standard 50,000lb (PSI, CUP?) service loads. The 75,000lb proof load blew it out though.

- In other tests the bolt lugs were ground down in stages until they were 0.1" (2.5mm) thick and they functioned fine with the standard service load. The lugs were then ground off completely and the third safety lug kept the bolt in the rifle when a standard service load was fired through it. It was crushed slightly. He then fired a proof load and it sheared the third safety lug off but the bolt only got pushed back 1/2" and got jammed in the rifle.


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UtahShotgunner
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Re: Testing a modified/weakened Mark X Action [Re: mauserand9mm]
      #303932 - 11/08/17 02:14 AM

Quote:

I think the results will be suprising.

Hatcher did some strength testing of Springfield rifles many years ago:

- He turned down the steel over the chamber in stages until it was 1/16" (1.5mm) thick and it withstood the standard 50,000lb (PSI, CUP?) service loads. The 75,000lb proof load blew it out though.

- In other tests the bolt lugs were ground down in stages until they were 0.1" (2.5mm) thick and they functioned fine with the standard service load. The lugs were then ground off completely and the third safety lug kept the bolt in the rifle when a standard service load was fired through it. It was crushed slightly. He then fired a proof load and it sheared the third safety lug off but the bolt only got pushed back 1/2" and got jammed in the rifle.




Hatcher and Ackley did some very interesting testing 'back in the day'.

I don't claim to have a tenth of their knowledge or expect to discover anything new. Just hoping to bring some information into the digital age. For shooters who (sadly) have never heard of folks like Hatcher or Ackley.


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UtahShotgunner
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Re: Testing a modified/weakened Mark X Action [Re: Vladymere]
      #303933 - 11/08/17 02:19 AM

Quote:

UtahShotgunner,

A thought on your head space testing. My understanding when testing head space is that the bolt should be stripped of the striker group and the extractor so they will not impart any friction to the turning of the bolt. The bolt is then allowed to close on it's own without assistance.

The above is not meant as criticism.

Vlad




Vlad,

No criticism perceived.

For a quick and dirty check to make sure that headspace is not excessive, I'll use a 'Field' gauge as shown in the pics. If the bolt had come close to closing I would have stripped the extractor for more careful testing.

Actually, in this case I would probably have just grabbed another bolt.



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Daryl_S
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Re: Testing a modified/weakened Mark X Action [Re: UtahShotgunner]
      #303941 - 11/08/17 07:25 AM

Ohhhh MANNNNNNNNNNNNNNN - looks at all those M98 bolts!!!!!!!!!!!!!!!

--------------------
Daryl


"a rifle without hammers, is like a Spaniel without ears" Edward VII


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mauserand9mm
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Re: Testing a modified/weakened Mark X Action [Re: UtahShotgunner]
      #303961 - 11/08/17 12:22 PM

Quote:

Quote:

...

Hatcher and Ackley did some very interesting testing 'back in the day'.

I don't claim to have a tenth of their knowledge or expect to discover anything new. Just hoping to bring some information into the digital age. For shooters who (sadly) have never heard of folks like Hatcher or Ackley.




I've only read Hatcher's Notebook and haven't looked at anything by Ackley. The stuff that Hatcher did was more empirical rather than what would be classed as scientific today - he was largely trying things without have a predetermined, expected, calculated result to compare against, but I guess that's how most practical discoveries are made.

I'm sure firearm manufacturers engineer the appropriate safety margins in their design but they'll never divulge this information - I guess for legal reasons for not wanting to have blame their way if someone modifies based on their data.


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Daryl_S
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Re: Testing a modified/weakened Mark X Action [Re: mauserand9mm]
      #303963 - 11/08/17 12:32 PM

I do remember one action that blew - that had a huge dovetail cut across the entire top of the front receiver ring. Different from this the Mk10 action, was that the dovetail was over the threads.

The Mauser and a Japanese action were barreled and chambered for a .270 barreled Improved Magnum case, I assume, the standard 2 1/2" belted magnum case.

A load that gave 'normal pressure & extraction' in the Arisaka action, blew the front ring off the top of the Mauser action.

--------------------
Daryl


"a rifle without hammers, is like a Spaniel without ears" Edward VII


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Grenadier
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Re: Testing a modified/weakened Mark X Action [Re: Daryl_S]
      #303966 - 11/08/17 03:20 PM



--------------------
~


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4seventy
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Re: Testing a modified/weakened Mark X Action [Re: UtahShotgunner]
      #304007 - 13/08/17 08:40 AM

Quote:


What I will be doing is firing a number of factory loads to see if they lead to any failure. If it is still together, I will move 'up' to the hot Turk ammo.

If there is no failure, I could load some rounds over maximum, but without a pressure gun I wouldn't know the failure point.

It is my suspicion that even if I reach the point of case failure, the action will withstand it, even with the top of the front ring milled away.




Quote:

I am not going to shoot this from the shoulder.




Utah, I'm looking forward to seeing the results of your tests.
Back in the early 80's I had the somewhat unpleasant experience of freezing up a 98 action due to extreme high pressure.
I was shooting a 270 Win from the bench at a range in Brisbane.
My third shot locked the action up and I had to use a block of wood and hammer to bash the bolt open.

The primer pocket and flash hole had expanded to what looked like twice normal size, and the cartridge case head had also massively expanded and flowed back into the front of the bolt and extractor .
Nasty stuff, but the action didn't suffer any damage at all. The 98's gas deflection design worked perfectly, and despite a shower of burning powder coming from the action, I didn't receive any serious burns to the eyes or face, and the stock was not damaged in any way.

The interesting thing was that a couple of weeks later, that rifle did the exact same thing again, fortunately with no damage to rifle or shooter.

Edited to add.......Both incidents involved factory ammo not reloads!

The 98 mauser sure is a great design, and super strong.


Edited by 4seventy (14/08/17 07:35 PM)


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UtahShotgunner
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Re: Testing a modified/weakened Mark X Action [Re: 4seventy]
      #304121 - 17/08/17 12:09 AM

Slight delay. . .

I forgot that the bolt that I installed was listed on eBay.
Just shipped it to its new owner.

As shown, I have others, but need to sort through them and come up with a combination that has proper headspace.


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