308 win in 1895 Chileno??

[JHeath]

I'm always glad to see Larry pipe up and when a certain Swede Mauser expert joins, it's like getting to watch Ali vs. Foreman again. I build rigging systems. Many components are marked with a "safe working load." This might be based on a design factor of 4 or 6 or whatever. Other components are sold with a "minimum breaking strength" and the user applies his own design factor. The pressure of 7x57 military ammo is only half the information. What is the failure strength of the action? If the action fails at 110,000lbs, and Larry is willing to run it at a design factor of 2 (55k vs 110k), but Multigunner insists on limiting it to 45k, the difference is really about design factor. Not pressure. And this is exactly like the donnybrook over low number 03s. Somebody asked about shooting 25k cast loads in 03s. People screamed because some of those rifles fail at 80k when they were *supposed* to fail at 125k. But the guy who runs them at 25k has a design factor of 3. Those who run full-house 60k loads through a double-heat-treated late 03 have a design factor of only 2. With the 95, knowing the ammo pressure only tells you the "official" safe working load. It does not tell you the design factor. A Hilti concrete anchor is sold with a DF of 4. A Crosby shackle is sold with a DF of 6. If I my spec requires a DF of 10, I can use those components by doing the math and oversizing them. If my spec allows a DF of 3, I can exceed the factory-rated safe working loads of those components. Wire rope has no listed safe working load, only breaking strength. That 95 action is not stamped with a safe working load. What is its breaking strength, and what is the required design factor? That's all that matters.

[Multigunner]

Metal fatigue is cumulative. If subjected to hundreds of rounds of ammunition that exceeds design specification the gun doesn't have to show obvious signs in order to have received irreparable damage that may result in a catastrophic failure at some future date.

If a rifle is designed for a specific working pressure considered safe and overbuilt enough to withstand a number of firings with out of specification ammunition not exceeding the proof test pressure but is then subjected to a steady diet of out of specification ammunition then metal fatigue will take its toll.
From what I have read on the subject of German proof testing of the Gew 88 they used a powder formulated to mimic powder degraded by years of storage under tropical conditions.
If a cartridge designed to generate 46,000 CUP was expected to generate 58,000 CUP after years of degradation then what pressure might one expect from a cartridge designed to generate 50,000 + CUP after being subjected to the same sort of degradation.

Lug setback is an obvious sign of ammunition exceeding the design specification. Micro fractures that once started by a few too many rounds of ammunition that exceed the design specs will continue to grow at every firing no matter what the pressure of later rounds is a sign the shooter has no way of knowing about.

I recently found photo copies from a re barreling shop manual given to me many years ago. These pages deal with re barreling military Mauser actions and inspection of candidates for re barreling. The entries on actions found far too degraded to be safe to re barrel are interesting.

[JHeath]

No. The CIP pressure for 6.5x50 Japanese is 43k. The CIP pressure for 6.5x54 Mannlicher-Schoenauer is 53k. Can you rechamber an Arisaka to 6.5x54 M-S? It exceeds the spec for the original chambering. Does that make it unsafe? No. Whether it's safe or not depends entirely on the ultimate strength of the action. It's got zero to do with ammo specs. If you buy a 7x57 Ruger No. 1, you can rebarrel it to .308. I can rebarrel my FN/Venezuelan 7x57 98 to .308. Whether it's a good idea for a 95 depends on the safety margins of that action. You cannot assume that 7x57 ammo pressures have a certain relationship to the action strength. You have to know the action strength.

[Multigunner]

"You have to know the action strength"
I think the numbers of 1893 actioned Mausers in 7.62 found with lug setback gives a good indication of the ultimate strength of the action compared to other action types also barreled or rebarreled to 7.62.

Metallurgy was fairly advanced in the late 19th century, but as working pressures of cartridges climbed new alloying agents and heat treatment methods were sought and developed precisely because confidence in the older actions to handle ammunition that gave better performance was waning. Between wars some nations imported higher quality proprietary steels to manufacture their own rifles precisely because the steel they normally used was no longer up to the task.

Factory specifications for the 7X57 ball cartridge were set at 3100-3300 Kilograms per square centimeter as the best level to allow good performance while not over stressing the action. They could have loaded the cartridge much hotter if they wished, but to do so would shorten the arm's service life and increase problems of excessive pressure of degraded ammunition, which every user of smokeless propellants had recognized as something not to be ignored.

The ultimate strength of the action when new and freshly proofed is not going to be the same as that of the same action after it has been subjected to thousands of rounds of ammunition that generates excessive pressures.

The early Mausers are an example of cartridges and rifles developed side by side. The 1998 Mauser action is an example of improvements in the basic design to take into account the higher operating pressures of more modern higher velocity ammunition types. Even now the WW1 era 7.92 cartridge is as powerful and efficient as the 7.62 M80 ball cartridge if not more so and the 7.92 heavy ball of WW2 is in the same ball park as the hotter M118.

I stated that the 48,000 CUP design pressure of the M80 ball is about as much as I'd subject a 93-95 action to. As the ordnance report made plain enough the German manufactured 7mm ball averaged the same 48,000 CUP, which you could round up to 49K if you wished to. Despite what I consider a wide range of pressure among the samples, from 43,000 to over 50,000 only a few of the sample cartridges exceeded the average pressure which itself exceeded the design pressure envelope a bit most likely due to storage conditions.
The pressures of the shoddy French manufactured ammo tested along side the German ammunition would be a worst case scenario, evidence of the rifles having a reasonable margin for error that was being pushed. I would not have wanted to use the French ammunition any more than the homegrown Boer Kortnek ammo which was known to cause catastrophic failures of new or nearly new 93 Mausers.

If one wished to take a converted Spanish Mauser in overall good condition and use hot 7.62 or .308 factory loads with the intention of only using the rifle occasionally and retiring it once the headspace increased beyond recognized safe limits that's up to them.
I don't doubt that many of the Spanish 7.62 rifles were sold off precisely because they showed signs of increased headspace while in service, they were certainly not intended as a main battle rifle at that time anyway. Once the actions suffered lug setback they were not worth further work since the receiver was to all intents and purposes shot. If not palmed off on the surplus market they'd have simply been scrapped.

[Tackleberry41]

Here we go again.

[Larry Gibson]

Here we go again.

Yup, some just can't get it through their head that the design specification for a cartridge and the design specification for an action are two different specifications. I also wonder if they comprehend the actual quality difference between various manufacturers of the SR Mauser actions. There is a considerable difference between German made M93s, M95s, and German and Swedish M96s compared to the various Spanish made M93 actions. Perhaps the best of the Spanish made actions was the Oviedo's. The earlier post of mine showed the 1928 Oveido M1916 that, besides who knows how many 7x57 barrels it went through, was used to shoot out 2 new .308W barrels with 10,000+ US M80 ball rounds plus probably several thousand .308W reloads that were found to be generating 64,000+ psi (transducer/strain gauge). The action was rebarreled even with what appeared to be .001 - .002 lug set back and is still going strong. Oh well, no sense trying present facts, such as actual pressure measurements of the concerned cartridges........which, btw, are completely in line with the original cartridge specifications used in the SR Mauser actions.

And as with the sleeved chambered .308W conversions in M95 Chilean SR Mauser, which is the real topic of this thread, they haven't grasped the fact it is the sleeved chamber that is the safety problem not the strength of the M95 action.

Larry Gibson

[JHeath]

Using lug setback to establish a "failure" threshold for an action is a good approach. Better than using the Kb threshold then applying a design factor.

I often deal with people in my industry who confuse their assumptions with fixed rules. Kind of like somebody in 1935 assuming that an N frame is only safe for historic .44 Special pressures because that's what is stamped on the barrel. Or conversely, like assuming that a Roller 7x57 can handle what a No. 1 can because that's what is stamped on the barrel.

The various historic cartridge pressures of a round for which a rifle was chambered, are not a "specification" of the action. They suggest what is safe, but don't say much about what is unsafe.

There's also the risk difference between likelihood and consequences. Safer to create a 50% chance of "Super face" in a 1911 by bulging a case, than to create a 20% chance of launching a 95 bolt through your head.

I am not drawn to marginal rifles with poor failure modes. Larry when guys with your experience are criticized for stepping over the caution tape with 95s or low numbered Springfields, I am on your side. Sometimes because the caution tape is 20' back from the edge. Other times because the caution tape is only 3' back from the edge but you can handle the risk.

[Larry Gibson]

JHeath

I no longer step over the caution tape with any action as I measure the pressures now. These days I do shoot loads in them having a measured comparable psi to the cartridges (actual measured psi's of original cartridges, not some quoted "specification") for which those actions were made. With my M91 Argentines (German made), my M95 (German made) and my M96 Swedish actions (Swedish and German made) there has never been any inkling of a problem. However, I have to admit those old .308W reloads, mostly with Hornady 165 SPBTs, at a measured 64,000+ psi were a few steps over the caution tape......

Looking at my old notes and knowing what I know now the velocities I was recording should have told me the loads were a bit too warm. However, "back in the day" I was going by the manual listed max loads and using CHE (Case Head Expansion) in load development. These days the manuals have toned down the "max" end of the old loads and we now know CHE is very unreliable......live and learn. None the less the M1916 Oveido survived and is still a good shootable action.

While I own 3 M1903s none of them are LSN'd '03s. I have never owned a LSN'd 03 myself. I have shot a few of them with issue M2 ball and cast bullet loads. I wouldn't hesitate to shoot one in good condition with a standard cast bullet load of say a 311291 over 28 gr 4895 with a Dacron filler. The measured psi is less than about half that of a 1906 cartridge. On the other hand my M1903A1 National Match Type II ( built on a SA DHT action) and my shooter M1903A1 (original SA DHT action and barrel) are shot with full service level M72 and M2 Ball level loads. I don't shoot my SC M1903A3 anymore since I found out it is as it came off the assembly line having only been inspected at Ogden Arsenal.

Excellent analogy using "the caution tape" btw.

Larry Gibson

[Multigunner]

What cartridge was the 1893 Spanish Mauser chambered for before the 7X57 Mauser cartridge was developed? What was the chamber pressure envelope of the Mauser Cartridges developed and marketed for use in the 1893 Mauser?

The Mauser 93-95 actions were designed to handle the pressures of cartridges that themselves were designed to deliver a specified performance, with a certain built in safety factor.

As I pointed out the action would when nearly new and in good condition handle at least one 58,000 CUP load without damage, it was never expected to handle magazine after magazine of cartridges at 58K CUP, if it had been the proof test loads would have generated far more than 58K CUP.
Some .308 Long Range target handloads found in the Hogdon loading data manuals generate aprox the same pressure ( in CUP) as the proof load used when the 93 was new.

The condition of far too many of the surviving 93 rifles suggests that even 7mm loads considered safe for the 98 actioned rifles in that chambering were a bit too hot for the 93. The Spanish manufactured 93 actions never had the reputation of being as strong as the original German made rifles, and more than likely any 7.62 chambered rifle with a 93 action that you'll run across will be a several times rebarreled Spanish knock off.

If Mauser had wanted a cartridge with the same velocity as the M118 they would have had no problem having the cartridge developed by DWM, but they would have had a much harder time producing a rifle to handle that sort of souped up 7mm in 1893.
The 7.65 Argentine Cartridge has much in common with the .308, but it was not loaded to the same pressure levels when the 1891 was the only vehicle for it.

Metal Fatigue is not only Cumulative its also "Accumulative", at a certain point crack propagation accelerates hastening failure.

I've said that I wouldn't want to subject a converted 93 action to a steady diet of pressures greater than 48,000 CUP , I suspect most people who have owned 93-95 actioned rifles would agree with me on that.
So what's so hard to understand about that?
There's certainly nothing to be gained by using hotter cartridges than the rifle was expected to digest.
Near as I can tell everyone on this board handloads. Its not as if the only cartridges available in 7.62 or .308 were those that generate the highest allowable pressures for those chamberings.
There's also no lack of stronger actions out there if one wishes to build a 7mm that they can soup up.

The Japanese sold Arisaka rifles chambered in 7X57 to the Mexicans, no doubt the Arisaka can handle just about any thing you want to stuff in it. The Mexicans bought up and built their own 98 actioned rifles as well, If the 93 was going to do the same job as well why go to the expense to replace it whenever possible?
By the 1950's the only countries still using the 93 were those who couldn't afford enough 98 rifles to arm all their troops, or constabulary where that applied. That includes Spain.
The rifle despite its many good qualities was obsolete. The Chileano was no great step forwards. Probably slightly better made with perhaps slightly better metallurgy, but not by much if any thing. Only real improvement was the small shoulder behind the bolt handle to form a very inadequate safety lug. Enough Boer Mauser bolts ended up in the shooters prefrontal lobes to suggest that little fix. Shoddy or degraded ammo in wartime was a fact of life.

[Larry Gibson]

Some still have a problem differentiating between CUP pressures and transducer measured pressures. Same still can't differentiate the difference between actual cartridge psi's and the maximum MAP specification for the cartridge. Boer Mauser bolts through their foreheads??????? The anti binding bolt guide on the M95 is oft referred to as a 3rd "safety lug" erroneously. Sheesh.......it never ends.......

Larry Gibson

[Tackleberry41]

We get different pressure and load data from companies in the US using the same equipment, much less a whole different method of measuring it in Europe. Apparently the Russians never even bothered with it as someone had to reverse engineer tokarev ammo to come up with some sort of pressure standard. Some of these limits do seem arbitrary. A report was posted on this site not long ago about flash hole size, which pretty much says, bigger works better. But nobody can seem to say where the original spec on flash hole size even came from. Doubt they put any testing into it to figure it out, and just said this size and its been that way since. Im willing to bet Mauser came up with the rifle, then they developed a load for it. It was right at the edge of the switch to smokeless and smaller calibers. And seems they would want a set velocity, with a max pressure, so long as a bullet went that fast, they cared little what the pressure was as long as it was below the max.

[Multigunner]

Some people can't recognize when someone else is trying to only compare the known records of Copper Units of Pressure of particular cartridges, and that Piezo electric measured PSI is not even secondary to those comparisons .
Interjecting in necessary lectures on the differences in CUP and PSI are nothing but a distraction from the major part of the subject in question.
There's zero information on Transducer readings of freshly manufactured 7mm Ball of the 19th century or the same ammunition after several years storage in a stable in Cuba because they did not have Piezo Electric transducers for many decades to come. Attempts to guesstimate the pressures by trying to duplicate the loads aren't likely to be productive since the propellants in use at the time haven't been available for generations. Testing any relic ammunition from those days is also unlikely to give even a ball park figure due to the effects of age no matter how well stored.

Luckily the U S Military procurement data sheets give the chamber pressures of most all 7.62X51 in use in Copper Units of Pressure as well as in the EPVAT transducer PSI measurements.
Metric Atmospheres and Kilograms per Square Centimeter may be confusing at times, but that is how Germany stated chamber pressures and Proof Test pressures in those days not in MegaPascals (MPa) as Europeans do these days.

[Larry Gibson]

"BTW; here is the U.S. Army's specification sheet for the M80 cartridge right out of TM 43-0001-27"

Notice the cartridge drawing on that page is of a .30-06 cartridge.
I mentioned earlier that those manuals are full of such errors, which is why you should go to the source material , the propellant procurement data........

You need to go back and look at the TM specification sheet again; The cartridge drawing gives the dimensions of the M80 Ball cartridge....2.8". That is a little shorter than the oal of the 30-06. No wonder we're having this discussion. The data sheets and manuals aren't in error.....your interpretation of them is.

Tomorrow I am going to test that 7x57 Chilean ammunition in the M95. I'm also going to test new Federal 175 gr SP factory 7x57 ammunition (no "degradation" of the powder from combat unless you consider gun stores as combat zones). Also will be testing some old Rem-UMC 175 factory ammo that never made it to a combat zone either.

To be fair also in .308W/7.62 NATO I have duplicated the M118 LR load using new IMR 4064 in LC Match cases with a Federal primer and 175 Sierra MKs. I will also be testing a couple lots of M80 and some M118 SB.

Time permitting I'll also test some South African .303 Mk 7, Remington 180 SP and 2 different lots of Winchester 180 SPs......the old Yellow box which has ball powder and new grey box which has extruded powder.

My measurements will not be in CUPs but in psi's. They will be comparative to each other if you understand nothing else. I will report the results tomorrow evening or on Wednesday.


Larry Gibson

[Larry Gibson]

Here’s the pressure data I’ve taken so far with the Chilean M95 7x57 Mauser using an Oehler M43 PBL. The M95 is in excellent condition, has been “sporterized”with the original milsurp barrel now 22” long. All measurements are in “psi’s”as to conform to SAAMI and C.I.P. psiMAP and PTc max measured with conformal peizo transducers. All the psi’s listed are not “absolute” as they were measured using the commercial and military grade ammunition made for such arms. As with measuring velocities, measuring the pressure on one day may not be the same as what is measured on another day can vary when tested even the very next day underthe same conditions. All testing was done using SAAMI testing procedures including the use of “reference” ammunition to obtain a “standard” psi measurement comparable to the standards set by SAAMIand C.I.P. All pressures shown are with the correction factor obtained through reference ammunition used. All velocities are muzzle velocities not screen velocities and are shown in fps. The psi figures are shown in thousands and hundreds, I. E.; 54,9 would be 54,900 psi.

All the following loads were tested yesterday. Ambient temperature ran from 70 to 80 degrees but all equipment including ammunition was shaded. Test consisted of 10 shots with the rifles switched after each test to keep the barrels cool. Two “foulers” were fired prior to each test string (as per SAAMI procedure). Yes it was a long 8+ hour day.

For the 7x57:
The SAAMI MAP is 51,0
The C.I.P. PTc maxis 57,0
Both are with transducer measurement.

Commercial Factory and hand loads:
Federal 175 RNSP; 49,9 2400
Rem-UMC 175 RNFMJ; 57,2 2311
Remington 175 RNSP; 48,2 2393
Winchester 175RNSP; 50,2 2376
My standard load 175 RNSP; 49,2 2334
Hornady Light Magnum 139 SPBT; 44,5 2624
My standard “light” hunting load 154 SP; 55,7 2579

Military Surplus:
CAVIM (Venezuela) 139 FMJBT; 46,0 2590
PS 1950 (Spanish) 154 FMJBT; 59,8 2442
PS 1951 (Spanish) 154 FMJBT; 60,5 2543
FAMME (Chile) 133 FMJBT; 55,3 2718
DWM 1918 (German) 172 Cupro RNFMJ; 54,8 2295

As we see the psi of both commercial and military ammunition made in 7x57 runs from 44,5 psi to 60.5 psi. Note the Chilean made military ammunition made for their own M95 Mauser gave a MAP of 55,3 psi, just under the C.I.P. PTc max of 57,0 psi.

Now, the original question of this thread was basically if 7.62 NATO ammunition would be safe in the M95s Chilean Mausers converted to “7.62. My response was if the M95s had new barrels most 7.62 NATO would be safe as most or the psi's of the ammunition over lapped. However, if the M9 5had a sleeved chamber and a rebored barrel then I would not feel it was safe. So now having some actual measured pressures of varied 7x57 ammunition let’s take a look at some actual pressures of varied .308W and 7.62 NATO ammunition actually measured with the same equipment.

The .308W/7.62 NATO test rifle was a M1909 Argentine M98 Mauser with a 24”heavy sporter contour barrel. The chamber was cut with a match reamer and headspace set to the minimum SAAMI specfor the .308W cartridge. Testing was done with the same Oehler M43 PBL using the same SAAMI testing technique as used testing the 7x57 ammunition. Reference ammunition was used to obtain the correction factor to give the psi as listed in thousands and hundred. The velocity is corrected to the muzzle and given in fps.


.308W/7.62 NATO:

SAAMI and C.I.P. MAP and PTc max; 62,000 psi as measured with transducers.

Commercial ammunition:
Winchester 150 PP; 61,7 2903
Remington 150 CL; 54,5 2924
Federal 150 PS; 57,3 2891
Winchester 180 PP; 57,7 2574

Military Ammunition:
M80 Ball WRA 68; 5 2,8 2790
M80 Ball LC 87; 61,2 2924
M80 Ball LC 90; 57,3 2852
CETME (Spanish) P 7.6 62; 58,7 2694
M118 SB LC 88; 62,9 2694
M118 LR (175 MK over 42.2 IMR 4064) LC 07; 59,9 2633
M852 MATCH LC 89; 59,0 2627
M852 duplication load (168 MK over 41.5 H4895, WLR, LCMatch case); 57,4 2670
M852 duplication load #2 (168 MK over 42.5 IMR4895, WLR,LC Match case): 61,3 2730

Thus we see here the psi of commercial .308W and military (U.S.) 7.62 NATO runs from 52,8 psi to 62,9 psi. Comparing the commercial ammunition psi’s to the M80 Ball psi’s we see there’s really not a lot of difference between .308W and 7.62 NATO. We also see that with the exception of 2 loads (one each commercial and M80 Ball) the rest fall within the psi’s the tested 7x57 ammunition psi range.

Those are the actual measured pressures of cartridges used in 7x57 and .308W/7.62 NATO rifles. Obviously the measured psi’s are different, as they should be, than the pressures listed on “data sheets”. All the measured pressures were within the SAAMI MPLM (Maximum Probable Lot Mean), EVPAT 7.62 criteria and the C.I.P. PK (Maximum Individual Statistical Pressure).

Larry Gibson

[CHeatermk3]

Thank you Larry for your excellent and illuminating work re the relative pressures of the ammo you tested.

Still glad I passed on the Chileno; found another one at a really good price in 7x57 to go alongside the one I already have.

[Multigunner]

I've mentioned before that the DWM ammunition produced from 1912 onward was intended for rifles like the Chilean 1912 Steyr a large ring Mauser action. I've also mentioned that during the Gran Chaco War older Small Ring Mauser rifles often failed when the newer hotter ammunition was used.
Besides the 98 actioned Mausers the combatants of that war routinely used Maxim and Madsen MGs chambered for the 7X57.
If IRRC Brazil bought a number of Maxim MGs in 7mm from Chile.

None of the military 7mm ammunition on the list was manufactured specifically for any Small Ring Mauser, during the Spanish Civil War even Spain was fielding WW1 surplus Gew98 rifles with barrels sleeved to 7mm and 7mm rifles with 98 actions bought from Serbia and other counties. I've not seen any problems of 98 actioned 7mm rifles being noted for severe lug setback.
George Orwell who fought for the Republican rebels wrote of complaints of the Spanish built 93 rifles failing in combat , sometimes with injuries to the shooters.
Use of the hotter post 1912 7mm cartridges explains why so many 1893-95 rifles exhibit lug setback.
Thanks for clearing that up, I'd hate to think those Small Ring Mauser actions were trashed by using only the proper standard 7mm Ball developed for these rifles when they were new.

[Larry Gibson]

Not worth wasting any more time........

[Larry Gibson]

Thank you Larry for your excellent and illuminating work re the relative pressures of the ammo you tested.

Still glad I passed on the Chileno; found another one at a really good price in 7x57 to go alongside the one I already have.

If you run across any Hornady 175 RNSPs you might try them under 47 - 48 gr H4831. I've had excellent accuracy in several different milsurp 7x57s with that load. The flat base and long bearing surface works well in the "oversize" Mauser bores. That hunting load with the Hornady 154 gr bullets also shoots to the sights on those regulated for the 154 gr FMJBT round, at least out to around 600 yards. If you've a rifle with sights regulated to the 133 gr Chilean FMJBT load (FAMME) then the Speer or Hornady 139 SPBT or the Sierra 140 SPBT over 52 gr H4831SC will duplicate the milsurp load and is very accurate in my M95 run at a sedate 49,000 psi.

Good going on finding another in 7x57.......much better that way.

Larry Gibson

And, they ain't bad with cast either......

[CHeatermk3]

I have about 250 ea. Privi 174gn FMJBT bullets I bought to try to scrub the barrel of Chileno #1; what do you think of those loaded over 41-42.5 gns of AA2700? BTW I have a virgin keg of IMR4895 on hand too...

[Tackleberry41]

Larry you and your facts and data, when has that gotten anybody anywhere?