Pressure, the 6.5x55, the 7x57mm and old Mausers

[R.W.Dale]

Quite frankly, you're not doing a very good job of it. You're coming across as fear-mongering and reactionary.



And that ain't helping you.



Um, what are you trying to do, again?

OK fair enough.

When things are unknown, unproven and the stakes of getting it wrong are high you err on the side of SAFETY

It may sound dramatic but when a small ring Mauser lets go the results are dramatic. They don't just blow the floorplate and lock up like a new firearm. They vent gas straight into your eye or flat out explode

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[crazysccrmd]

I think what RW is trying to say is that not all of these older rifles are in the condition to fire full power high pressure loads anymore. Though most can handle it and keep going without problems at some point one will fail. Unlike the 98 actions that have a third locking lug to help stop the bolt from blowing backwards and the designed ability to vent gas away from the face the older ones do not. You just have to work up loads in your individual rifle and keep checking for signs of stress, not automatically assume the rifle can handle it.

 

[R.W.Dale]

I think what RW is trying to say is that not all of these older rifles are in the condition to fire full power high pressure loads anymore. Though most can handle it and keep going without problems at some point one will fail. Unlike the 98 actions that have a third locking lug to help stop the bolt from blowing backwards and the designed ability to vent gas away from the face the older ones do not. You just have to work up loads in your individual rifle and keep checking for signs of stress, not automatically assume the rifle can handle it.

Yes. And that involves maintaining some sort of pressure ceiling and checking checking and checking headspace.

And that doesn't involve putting your reading glasses on and holding a 4 or 5th firing neck sized only case at arms length underneath a lamp and proclaiming "looks good".

It means using a no go gauge and noting that bolt handle stops in the same place it did the last time you checked.

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[Slamfire]

The question of the true design parameters for the early Mausers is a difficult question. Inferences may be made from ammunition, from catalogs of the period. If you examine your Ludwig Olsen, that is what he did, the data on the 7X57 mm cartridge goes from 35 Kpsia up to 49 Kpsia.

The most true and reliable source would be Paul Mauser’s design notebooks. Those would be a primary source. Everything thing else becomes secondary.

There are lots of errors that creep on secondary, tertiary, subsequent editions. Just yesterday I was reading a book called “devil boats”. I was surprised to find, according to the book, that at the time of Pearl Harbor that the Navy was using the “M1904 Springfield”. I have never heard of a M1904 American service rifle, at least not before. You would think factory manuals would be a good reliable source, but then this week I was at a friend’s house. We were looking in his 1963 Chevy factory manual trying to find the specifications for clutch plate thickness. Could not find it. Even though the transmission was original to the vehicle, my friend had to figure out his own removal sequence, because it is not in the factory manual. The exploded diagram of the “not my transmission” was of no help at all.

I have written technical details of a design, passed it out, and seen how marketing and the Loggy’s, muck it up in their brochures and manuals.

I really doubt that Paul Mauser’s notebooks exist any more, I have no doubt that just like today’s arms designers, if you asked the Mauser Corporation, they would not tell you. They would have considered that proprietary, today, there is too much risk in telling people the design limits of firearms because reloaders will load to the limit and beyond.

Some of the members of SAAMI make and sell ammunition. That ammunition has to work in everyone’ rifle. If the ammunition blows up a rifle than there is the potential of a lawsuit. So when they determine standards, they have to analyze risk, profit and loss.

SAAMI has decided that making high pressure ammunition is too risky for these old military actions. Maybe they were too conservative, maybe they got it all wrong. But for the ammunition makers the risk represents real dollars, jobs, and they are not willing to accept the risk.

For those who are insistent on the quality of these actions and the pressure levels they can sustain, why don’t you put some skin in the game?

It is good that you are actually firing these things with modern ammunition. You are at least doing that. If your rifle blows up we will hear about it and if it does not break you can talk about it. But expand the discussion: make a commitment to the community. Personally guarantee that anyone who shoots these old rifles with modern high pressure ammunition, if the rifle breaks, you will buy them a new one. If they are injured, you will cover the costs.

Having real financial skin in the game will change this debate over night.

The supporters of these old actions can pool their money, post a bond, provide conditions and contact information, sit back confident in the future and with the satisfaction that they were right.

Money talks.

 

[willypete]

R.W.Dale, your assumptions that people are ignorant or stupid are insulting, as is your insistence that bad data and emotional arguments take sway over numbers and destructive tests.

Again and again, it has been demonstrated that you are wrong, and yet you continue with your rhetoric. I guess what they say about arguing with idiots is true. I'm done with you. Go take up 35W on his offer to exchange your reloading tools for cash for anxiolytics; you'll be much happier and safer if you don't reload period. That's the safest course after all, right?

For those who are insistent on the quality of these actions and the pressure levels they can sustain, why don’t you put some skin in the game?

My skin is already "in the game." I'm the one firing the rifle.

The supporters of these old actions can pool their money, post a bond, provide conditions and contact information, sit back confident in the future and with the satisfaction that they were right.

Or we can just shoot the damn things and not play games of one-upmanship over the internet.

 

[R.W.Dale]

OK lets keep to the FACTS


308 Winchester = 62,000 psi

Hottest commercial 7x57 = 57,000 psi

What leads you to the conclusion that an additional 5000psi is completely safe ASSUMING 57k psi is?

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[35 Whelen]

Honestly, I had become a little bored with the drivel, but now this is becoming humorous...sporting if you will!!

They don't just blow the floorplate and lock up like a new firearm. They vent gas straight into your eye or flat out explode

WOW...in a few minutes of research (far less time than I'll spend typing this post, hint, hint) and looking at my own 1916, since that seems to be the action in subject, I found a gas release port on each and evey rifle:















...and unless you mount a parascope, sideways with the ocular lense facing left over the front receiver ring, looks to me like it's going to be very difficult for a ruptured case head or a blown primer to "vent gas straight into your eye".

What leads you to the conclusion that an additional 5000psi is completely safe ASSUMING 57k psi is?

Going back to facts (FYI, facts are the opposite of conjecture which is synonymous with rectal extraction)

"In C.I.P. regulated countries every rifle cartridge combo has to be proofed at 125% of this maximum C.I.P. pressure...."

That'd be a little over 70,000 PSI. What was it H.P. White proofed these rifles at....98,000? Hmm....

You know, if I don't stop reading these posts, I may be the one who needs the Xanex!!

35W

 

[R.W.Dale]

You really don't have a clue do you.

You think that just because there's a gas vent hole that in the event of a case failure all 60k psi worth of superheated gas will go out that little hole and the shooters hair wont even be ruffled.

Ever wonder why the cocking piece on a large ring Mauser is so different compared to a small ring?

Its because without the gas deflection flange provided by the large ring cocking piece and a couple of striker changes in the event of a case rupture superheated gas has just as easy a shot straight back along the bolt body or even through it to the shooters face as it does to make a 90 degree turn and all go out that vent hole.

The large gas flange at the rear of the Mauser bolt has been copied or reproduced in some way on modern rifle designs, but the gas deflecting step in the bolt shaft has been left out. The Mauser bolt has a step towards the rear of the bolt that mates with a step in the receiver which prevents the gases getting a straight shot at the shooter under the flange.

http://hunting.about.com/od/guns/l/aastboltsofCg.htm

Another safety feature of the Model 98 is the large gas shield at the front of the bolt sleeve to protect the firer’s eyes from hot gas and brass splinters in the event of a pierced primer or case-head separation. Oblong holes in the bottom of the bolt body serve the same purpose.

http://www.americanrifleman.org/m-articlepage.aspx?id=1938&cid=3

In addition, the M-98 incorporated gas-venting holes in the bolt body that direct gas downward into the magazine and a gas deflecting flange on the bolt sleeve to protect the user from a pierced primer sending back gas along the locking lug raceways. It is said that Paul Mauser’s losing his sight in one eye was the impetus for all the designed-in gas safety features.

http://www.chuckhawks.com/mauser_gewehr98.htm


To quote the wiki about the 98

"The action features two large gas relief holes and a gas shield on the bolt sleeve designed to protect the users head in case of a primer or cartridge rupture or detonation. When the action suffers a catastrophic failure these safety features deflect escaping gas and eventual debris away from the operator's face."

http://en.m.wikipedia.org/wiki/Gewehr_98

You also fail to fundamentally understand the reasons behind proof loads.

A proof load tells the manufacturer that if something goes wrong that rifle wont explode then for a single point event. IT DOES NOT Mean the firearm can be fed a steady diet of near proof loads and not eventually fail as with the case of a small ring in 308 win

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[Slamfire]

Even though the small ring Mausers have a gas vent, it is not particularly effective in blocking gas escape back into the action. As you can see in these pictures the magazine well has been expanded, the bolt stop is sprung, extractor and collar blown out of the action and the receiver ring split. This is one of those Spanish 308 Winchester conversions.











The M1903 has a similarly ineffective breeching system and later the “hatcher hole” was added. The hatcher hole is a gas vent on the left side of the receiver, same basic location as on the small ring mausers.

You might be able to see it in the pictures. This National Ordnance receiver was so soft that it developed excessive headspace and the cartridge ruptured. As you can see in the photographs gas escaped everywhere and the shooter was injured.

This shooter is still experiencing problems:

i was the guy who had the National Ordnance 03A3 blow up in my face. I like you am still pushing people away from those ticking time bombs they call rifles. I had one surgery after I last conversed with you. Had to have a tooth removed, piece of brass was blown into my nerve and the sun still burns my eyes from absorbing heat.

http://www.jouster.com/forums/showthread.php?t=2893

 

[bobnob]

I have a Berlin DWM Mauser manufactured in 1897, I am told its probably a Mauser 95 design, but its marked "MOD. MAUSER 1897".

It has been rebarreled in .308 Win. Was subject of a post on here some time ago.

I shot factory loads through it on and off for about 25 years, as well as a variety of handloads that were on the mild side.

My instincts tell me it is fine for the factory loads, however in deference to the age of it I feed it relatively mild handloads now. ie 150g bullets around 2700 fps or so, using 44g of AR2208 (Varget).

I imagine this would be as safe as you could reasonable expect. Any thoughts?

 

[35 Whelen]

I imagine this would be as safe as you could reasonable expect. Any thoughts?

I'll go ahead and answer for R.W. and SlamFire:

"Do NOT under any circumstance fire this rifle with any loads that develop chamber pressures exceeding that of the 22 Short rimfire. Doing so will blind you, blow both your hands and most of your toes off. Also, I read on another internet forum about a guy who did this very thing and from that point on, all his children were born naked!"

My thoughts? You're doing exactly what I do with mine, except I don't shoot factory loads. Your load should be way below the real limits of these actions. My load of pulldown 4895 propels a 150 gr. Remington a shade over 2700 fps. If this load ruins my rifle, then I don't need it and I'll use it for a trotline weight.

By the way Slam, nice Mauser pictures, but I think you've already posted them. What's the deal with the blown up rifles and NO explanation, no story? Was it factory loads? Handloads? Possible bore obstruction? It's like your kids getting in trouble at school yet saying "I wasn't doing anything wrong!"

The one single rifle I personally witnessed blow up was a custom 25-06 built on a nice commercial '98 Mauser action. The old guy had fired several of his handloads (IMR-4831 & a 120 gr. Hornady as I recall) with no problems, then suddenly he's standing there with the buttstock, broken just behind the tang, in his right hand, and the remainder of the rifle in his left. Explanation? His never ending desire to run loads as hot as possible.
So, no, I KNOW the gas port won't handle all the pressure, but the gentleman was relatively unharmed save a small metal fragment in his face.

IT DOES NOT Mean the firearm can be fed a steady diet of near proof loads and not eventually fail as with the case of a small ring in 308 win

I don't where you got the idea that anyone here thinks the rifles in question can be fed a steady diet of "near proof loads".

35W

 

[R.W.Dale]

Well if proof loads are 70k psi and factory. 308 ammo generates 62k psi that's shooting ammo that's only 10% below a 125% proof load

That's awefully close and is in fact closer to proof loadings than it is hot 7x57 cip loading.

And if the KB you witnessed had been with a small ring Mauser the shooters injuries would have required immediate medical attention as per the safety improvements his 98 has compared to your small ring.

Any way you care to slice it factory 308 win is way overpressure compared to even the hottest 7x57 loadings

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[USSR]

I'll go ahead and answer for R.W. and SlamFire:

"Do NOT under any circumstance fire this rifle with any loads that develop chamber pressures exceeding that of the 22 Short rimfire. Doing so will blind you, blow both your hands and most of your toes off. Also, I read on another internet forum about a guy who did this very thing and from that point on, all his children were born naked!"

A cheap shot, 35 Whelen.

...I KNOW the gas port won't handle all the pressure, but the gentleman was relatively unharmed save a small metal fragment in his face.

Oh, as long as it was just a small metal fragment. Not using small ring Mausers for high pressure loads goes back to before most of us were born, so it's not like R.W. Dale and SlamFire are making this stuff up.

Don

 

[R.W.Dale]

So, no, I KNOW the gas port won't handle all the pressure,

apparently not till recently as evidenced by your previous statement of.. (bold added for emphasis)

WOW...in a few minutes of research (far less time than I'll spend typing this post, hint, hint) and looking at my own 1916, since that seems to be the action in subject, I found a gas release port on each and every rifle:


..and unless you mount a parascope, sideways with the ocular lense facing left over the front receiver ring, looks to me like it's going to be very difficult for a ruptured case head or a blown primer to "vent gas straight into your eye".

So where are we now

dont own headspace gauges

dont know what the rifles headspace is

found some higher then 50k psi 7x57 loads on the internet that still fall way short of 308 pressures

saw a k98 blow up where it protetected the shooter from injury with several key features your rifle lacks

proof loadings for the original chambering are only a few thousand PSI hotter than 308

please enlighten us as to how all these factors brings you to the conclusion that firing factory 62,000psi ammo in a small ring is OKAY

 

[Slamfire]

Jerry Kunhausen’s book “Mauser Bolt Actions” discusses these early actions in several sections.

ON page 71, he states that M91-M96 receivers that he had tested had steels roughly equivalent to SAE 1020, 1025, 1030. He states one Spanish made receiver was below 1020. These steels are so low grade that today they are used for rebar.

Looking at data on Matweb, the low carbon steel used in these early receivers is not used for complicated parts, unheated it is used for rebar, if heat treated for medium duty shafts, studs, bolts and nuts. I did a composition search and found AISI 1117-1118 steel, which is similar in composition to Springfield Armory Class C steel used in the Krag's and in the M1903. I could not find something that was just carburized and quenched, which was the single heat treatment at Springfield and what early Mauser plain carbon receivers would have experienced. I found data for 1 inch round AISI 1118 mock carburized, reheated to 1450 F, quenched, tempered. This is similar to the M1903 double heat treatment. The Ultimate strength is 103,000 psi, yield 59,300 psi, elongation at break 19%. For something similar to WD2340 Nickel steel, which was used at Springfield in 1927, I found one inch round AISI 4820. For that material, mock carburized, 1450 F reheat, water quench, the ultimate strength was 163,000 psi and the yield strength was 120,000 psi, elongation at break 15%. Many modern receivers are made from 4140. For a 1 in round AISI 4140 Steel, normalized at 870°C (1600°F), reheated to 845°C (1550°F), oil quenched, 260°C (500°F) temper, ultimate strength 270,000 psi, yield 240,000 psi, elongation at break 11%


Just looking at the material properties, you can see how material technology improved as the century progressed.

Kunhausen makes the claim, on page 85, that the 7.62 mm CETME cartridges produce pressures in the 41,500 to 42,000 CUP range. No reference given and if you search on the web you will find statements that the 308 cartridges made for these actions had 130 grain bullets to reduce pressures.

Figure 79 shows a M93 receiver that the Spanish converted to 7.62mm CETME. The receiver lug surfaces are set back .009” from use.

This post from another forum has interesting data on these small ring Mausers: (emphasis mine)


http://www.surplusrifle.com/shooting2006/spanishmauserrevisited/index.asp

A substantial amount of information has been compiled concerning the safety and reliability of the Spanish built FR-7, FR-8, and Guardia Civil rifles. The FR-7 and Guardia Civil 1916 rifles are built on the 1893 pattern rifle. This particular design employs a two-lug bolt system, as opposed to the 1898/1943 model rifles adopted by the Spanish government.

The 1893 pattern is a small ring Mauser action, 1893 pattern, with the two-lug bolt system.The 1943 model employs the much-improved three-lug bolt system (two locking lugs and a non-bearing safety lug). The model 1943 is a large ring rifle that was originally chambered in 8X57. The FR-8 is a converted 1943 model. The FR-7 is constructed on the 1893 pattern. Many of both the 1893 pattern and 1898 pattern rifles were converted to the 7.62 x 51 mm NATO cartridge.

It should be noted here, that the small ring 1893 Mauser in 7 x 57 mm caliber was designed for a maximum chamber pressure of 46000 cup. The 7.62 x 51 mm NATO round topped with the standard 147 grain FMJ military ball bullet generates a maximum of 50,000 psi of chamber pressure.

The commercial .308 Winchester round topped with a 150-grain bullet generates an average working pressure of 52,000 cup. The .308 Winchester’s maximum pressure is limited to 55,200 cup, well above the pressure for which the 1893 pattern and the 1916 short rifle were designed. The 1898 type 1943 Mauser rifles are perfectly capable of withstanding the higher pressures of the 7.62 NATO cartridges. However, a prudent person would/should have this model Mauser and other military surplus weapons checked by a competent gunsmith using the appropriate testing methods prior to firing them.

I currently own both an FR-7 and a Guardia Civil rifle (1916 Short Rifle). Both appeared in excellent condition when purchased. However, upon having them examined by two local Mauser experts, Cliff and Charles Houston of St. Petersburg, Florida, they found that the headspace was beyond what is considered to be a normal range. This was determined by the use of field and go/no gauges.

An additional portion of their examination of these two rifles concerns the steel used in the construction of the 1893 pattern receivers of these rifles. The Spanish steel was of an inferior grade (as compared to the original German produced models). Unfortunately, this was a common practice of Spanish arsenal made rifles. Apparently they had a propensity for disregarding generally accepted principals of metallurgy. The hardness of the two receivers was determined through the use of a low tech, but thoroughly reliable device called a Scleroscope. This simple, but reliable device has been in use in numerous types machining and manufacturing industries for many years. It consists of a glass cylinder marked with a Rockwell “C” scale, and a ¼ inch alloy ball of known hardness. The cylinder is placed over the receiver, and the ball released. The level to which the ball rebounds to is noted on the scale. Upon comparing the level to which the ball rebounded when compared to dropping the ball on a piece of hardened tool steel it is readily determined that the steel used in the manufacture of these two rifles is of an inferior (softer) grade as opposed to rifles manufactured by German or Belgium companies.

An additional attribute of the Scleroscope lies in the fact that this device does not penetrate the surface of the weapon being evaluated. Other devices penetrate the surface, and therefore will mar the finish on the rifle being evaluated. These other devices, while undoubtedly more definitive, are more cumbersome to use, and substantially more costly. The Scleroscope is simple to use for the average person, is very portable, and requires no batteries or sophisticated knowledge for its use.

The combination of a two-lug bolt system, a soft steel receiver, and a rifle chambered and rebarreled for a cartridge that generates substantially higher chamber pressures than what the original design was meant for can be a prescription for disaster.

Unfortunately, many of these rifles that were re-chambered to 7.62 NATO caliber and marketed and advertised for sale in national publications as safe for use with both 7.62 NATO ammunition and .308 Winchester, with scant warning to the consumer. Therefore, caveat emptor (buyer beware) is the watchword!!!

 

[Slamfire]

Another post on the these old M93 type actions.


http://www.thehighroad.org/showpost.php?p=7822362&postcount=12

I recommend... ________________________________________

that you honorably retire the rifle.
My experience with the Spanish '93-type actions is that they are not suitable for rebarreling to any modern cartridge at all.
They are all soft (many years ago, I watched an old gunsmith squash one in simply tightening his action wrench onto it. When he noticed that the barrel shank wouldn't thread back into the action, and realized why, he simply took the receiver out of the wrench, laid it on his bench and smacked it with a big brass hammer until he could screw the barrel back in).
With pressures higher than about 40 KPSI (virtually all modern CF rifle cartridges), the locking lugs will set-back into their seats very quickly, increasing headspace until the bolt becomes hard to open and case heads separate. Several years ago, a customer (and friend) decided he'd like to make up a 7.62x39 rifle on just such a '93 Spanish action. I couldn't talk him out of it, so made and fitted a barrel for him. In shooting about 200 rounds of Wolf ammunition, it battered itself into just the state I described above.
Just my recommendation, but not based on hearsay.

 

[Slamfire]

Found the pictures but not the story. Looks like the event created a new gas vent hole.

I think this is a Swedish action from the gas port hole on the bolt.