there is some controversy over how adequate the MAS-36 action is for the 7.62x51 nato loads.

Point is do you want this for collecting for shooting.

 

Both, unless substantial evidence convinces me the latter is a bad idea.

 

This comes up over and over. Drift back through some of the comments in earlier posts on this subject. The MAS 36 is plenty strong enough to rechamber to 7.62 NATO. Like all such "Disaster" rumors, no evidence is ever found. Many MAS 36 custom sporting rifles in Asia were barreled up to much hotter cartridges. You may be right about the number converted. I believe Golden State Arms also converted a few and probably some other companies, but you rarely see them.

 

Per Kelt, in a previous message

The design maximum safe working pressure of the guns built to fire that cartridge is listed as 3.500 bars or 50.750 Psi by the SNPE (Societee nationale des Poudres et explosifs), as a comparison the 7.62x51 Nato load is listed as 3.600 bars or 52.200 Psi by the SNPE.

With that said, 7.5x54 is still available but now expensive. Depending on how much you plan on shooting, get two boxes and then reload them

 

Per Kelt, in a previous message


With that said, 7.5x54 is still available but now expensive. Depending on how much you plan on shooting, get two boxes and then reload them

I believe this to be wrong. That is not the working pressure of the gun itself. That is the working pressure of the ammunition. I have been working on guns 40+ years and have yet to see an MAS 36 "Blown up" in the original chambering or a modified gun. That is amazing when you consider that people will load just about any ammunition in a foreign gun that they can beat the bolt closed on. I have never even seen a MAS 36 bolt or receiver with setback.

 

You might want to read more. I remember him posting that the design was such that an obstruction in the barrel would not cause a locking failure. That is quite a bit of pressure. I believe that a few MAS 36 rifles were built into 7.62 NATO sniper rifles. The receivers appear to be of a high carbon steel, heat treated through, and at a low hardness much like the Arisaka.

 

Normally if the obstruction is a distance from the chamber the action suffers hardly at all. An obstruction in front of the chamber will increase back thrust on the bolt.
The Arisaka has metallurgy similar to that of the 98 Mauser. Case hardened, forged, and low carbon steel.

 

kelt posted this long time ago ... Hunting rifles built for the civilian market by MAS on Mas 36 receivers and chambering the 10,75x68 and 8x60S have been used for décades these rifles were individually proof tested twice with test cartridge developing 30% pressure over the maximum pressure rating of each caliber.

Patrick

 

30% does not like anything special. The big thing is what are the operating pressures of the 10.75 and 8s mm rounds that are being discussed here.
Also what is number of such rounds that will run through these rifles of what is obviously hunting ammo.

 

do yourself a favor and do a search of the forum for the conversions and read the older posts on this issue, there had been many good discussions on the topic.
To use the search function of the boards, go to the top of the boards and there is a box (Search Community), write in what you are looking for then hit the magnifying glass, it will pop up the results or you can do an advanced search in the different forum you want to look for the information in for that result.

Patrick

 

It seems every single one of these 7.62/.308 conversions has warnings of somehow they will blow up and each and every one of them has zero evidence of one blowing up! At most a picture will be shared with no context. Then people bring up pressure differences, ignoring the fact that they were all measured differently, and never wondering why two almost identical cartridges have wildly different pressures reported when they use the same powder, case and bullets. They are all full power rifle cartridges; the pressures will always be similar. Doesn't matter what caliber it is.

FWIW, these MAS36 ,308 conversions are bad because Century cut the back of the stock off and in doing so the stock isn't bedded anymore.

 

The best argument I can come up with is the '98 Mauser was never intended to be used for the .308 Norma Magnum either, and that is an intense round. The '99 Savage moved up to the .308 and .284 by REMOVING material from the receiver so they would fit. The basic dimensions and metallurgy remained the same. True, it pays to be cautious and look into the strengths of an action. A Mauser is not just a Mauser. I cut apart a Swedish Mauser someone had rebarreled to .264 Magnum and it was "Welded together". An experienced Gunsmith did this and should have known better. Swedish receivers are known for developing set back. I refused to work on '03 Springfields because they DO have a recorded history of failure. I know of only one case of someone being killed by a blow up. It was local and the man was shooting a (If I remember correctly) 6MM Lee Navy. The Coroner reported the cause as a reloading accident. Many people have "Close ones" every year, but it usually involves not paying attention somewhere along the line. Caution is good, but undocumented rumor is not.

 

The best argument I can come up with is the '98 Mauser was never intended to be used for the .308 Norma Magnum either, and that is an intense round. The '99 Savage moved up to the .308 and .284 by REMOVING material from the receiver so they would fit. The basic dimensions and metallurgy remained the same. True, it pays to be cautious and look into the strengths of an action. A Mauser is not just a Mauser. I cut apart a Swedish Mauser someone had rebarreled to .264 Magnum and it was "Welded together". An experienced Gunsmith did this and should have known better. Swedish receivers are known for developing set back. I refused to work on '03 Springfields because they DO have a recorded history of failure. I know of only one case of someone being killed by a blow up. It was local and the man was shooting a (If I remember correctly) 6MM Lee Navy. The Coroner reported the cause as a reloading accident. Many people have "Close ones" every year, but it usually involves not paying attention somewhere along the line. Caution is good, but undocumented rumor is not.

The old Mark X made by Zavastia that was a commercial 98 mauser commonly made at the factory in magnum calibers and was considered suitable for that task. The point being the 98 mauser is an improvement over a a swede 96. It is possible that post war world II Mark 10 mausers have better metallurgy than those made in 1900.

 

Norma sent reamers and chamber specs to American gunsmiths specifically for use in the 98 Mauser action. The '98 Mauser was made with cheap steel and then case hardened. The French MAS is high carbon steel heat treated all the way through and very tough. It is almost as if they were working with the Japanese when designing it.

 

Were all 98 mauser made of cheap steel considering that they were made in numerous places over periods of many years. So I tried google and found a Post by whom I assume is the same DOC AV that posts here

Below the Arisaka also use the same metallurgy

What type of metal?
DocAV

Aluminum
Mauser Actions used a steel of Low carbon content, that approximates to SAE 1030-35. ( as do Arisakas as well)
There is NO "Heat treatment" as used with modern Alloy steels such as 4140 etc. The Finished receiver is "Case Hardened" ( Carburised) to increase the carbon content of the surface steels, in the high wear areas. The secret of the strength of Mauser (and more so Arisaka actions) is the bolt to receiver design, and the forging of the steel before machining to make sure "all the grains" are lined up, and the Case hardening ( usually only 1 or so millimetres depth) is for the wear resistance and impact resistance of such areas as Bolt locking shoulders, Receiver ring, etc.

E arly Mauser "Case Hardening" was done in the traditional method, the receivers were packed in Powdered Bone charcoal, inside a sealed iron "can" or Case" and the lot placed in a Furnace, to reach the appropriate "Carburisation" temperature, for a set amount of time ( Carburisation deepens on a time line, according to temperature.)

After the heat is removed, the Metal is allowed to air cool, in such a way that there is no distortion.

Tempering may also be used in this process.

If prefential case hardening is required, then the "soft" parts are coated in porcelain clay, to preven the contact with the Bone charcoal.

BY WW I, the German Steel and Chemical industry had developed a more certain case Hardening process, based on a Chemical Salt bath, which was heated to carburising temperatures...This is the "Kasenit" process, using Potassium-Ferri-Cyanide to supply the carbon necessary for the carburization.

This shortened the carburisation process in Time, and made for a more controllable case hardness. THis was used thru WW II on all Mauser Rifle receivers, by all makers in Europe. The Japanese used a similar system in the Arisaka production as well.

If the process was overdone, one gets the "Glass-hard" surfaces of receivers seen in late war ( 1944-45) Brno Mauser production. These require spot annealing ( carbon electrode) to soften enough to allow D&T for Scope base screws.

If one needs to work on a receiver, the solutions are simple...A full anneal (Normalization) will reduce the receiver to soft steel, and may even burn off some of the "Case"; TO return it to original case hardening, one has to use either "Kasenit" Bath ( Difficult and "Toxic" for the Home Gunsmith) or the older Case with Bone charcoal method)..
....or simply spot anneal using a resistance carbon electrode ( the type used in old Arc Light Movie Cinema projectors) sharpened to a point, and a high amperage current from a "Stick welder" used to soften an area preferentially ( heat sinks and paste required to prevent unwanted heat spread.).

Distortion in (M96) receivers is due to too rapid cooling ( air or salt bath) and improper temperatures.

Good luck,
Doc AV
AV Ballistics Film Ordnance Services

 

What nonsense. Nothing but internet rumor. Arisakas were my favorite gun to sporterize because they were in the 4140 range with their material. I have made bolts, shortened receivers, lengthened receivers, and heat treated them. I had access to a Rockwell tester but only a small tool room furnace, so serious case hardening was not an option. If you grind about .030 (or less) off a 98 Mauser or a Moisin it is soft underneath. You can heat treat that area until you pass out from the heat and it will not get hard unless you introduce carbon, no matter what you use or do to quench it. Not so with high carbon steel like 4140. If you anneal an Arisaka receiver or bolt and then re-heat treat it, you can follow the specs for drawing back for 4140 and it will RC test EXACTLY like 4140.
The MAS 36 is high carbon steel. I did some machining on a receiver and can tell the difference. I never had a scrap receiver to test for HT, but would bet it is about the same make up as an Arisaka. It would be nuts to use 1018-1020 steel and leave it soft inside and out. Should you have a scrap MAS 36 receiver around, cut a piece off and heat it up cherry red and then drop it in a can of oil. When it cools, take a file and try a cut on the original receiver and then the HT piece. I bet there will be a huge difference. You can also use a piece of rifle barrel. Most high power barrels after black powder are in the 4140-4150 range.

 

What nonsense. Nothing but internet rumor. Arisakas were my favorite gun to sporterize because they were in the 4140 range with their material. I have made bolts, shortened receivers, lengthened receivers, and heat treated them. I had access to a Rockwell tester but only a small tool room furnace, so serious case hardening was not an option. If you grind about .030 (or less) off a 98 Mauser or a Moisin it is soft underneath. You can heat treat that area until you pass out from the heat and it will not get hard unless you introduce carbon, no matter what you use or do to quench it. Not so with high carbon steel like 4140. If you anneal an Arisaka receiver or bolt and then re-heat treat it, you can follow the specs for drawing back for 4140 and it will RC test EXACTLY like 4140.
The MAS 36 is high carbon steel. I did some machining on a receiver and can tell the difference. I never had a scrap receiver to test for HT, but would bet it is about the same make up as an Arisaka. It would be nuts to use 1018-1020 steel and leave it soft inside and out. Should you have a scrap MAS 36 receiver around, cut a piece off and heat it up cherry red and then drop it in a can of oil. When it cools, take a file and try a cut on the original receiver and then the HT piece. I bet there will be a huge difference. You can also use a piece of rifle barrel. Most high power barrels after black powder are in the 4140-4150 range.

Does the Garand action after you grind the surface become soft or hard. Fpr an action do you want the interior to be ductile or hardened?

 

What an ignorant question. It does not "Become" anything. It stays hard. It is a totally different material. This is the French Forum. Cut a rifle receiver from the MAS 44/49/49/56 series and it is hardened all the way through, but probably not above 35-36 RC, if that. I would be willing to bet that it is also in the 4140 series of steel. I am not a professional heat treater and neither are you. But, I have done a lot of heat treating and sent a lot out to heat treaters from places I was employed at. You obviously have done neither. I followed that linc you had posted and that guy does NOT know what he is talking about. You do not have to use a salt bath to quench 4140. It will jump up to 56-58 RC in oil. 4140 will crystalize in a water quench, so I have no idea what salt slush will do to it. I have never seen any reliable source condoning the use of a salt bath for heat treating 4140.

 

What an ignorant question. It does not "Become" anything. It stays hard. It is a totally different material. This is the French Forum. Cut a rifle receiver from the MAS 44/49/49/56 series and it is hardened all the way through, but probably not above 35-36 RC, if that. I would be willing to bet that it is also in the 4140 series of steel. I am not a professional heat treater and neither are you. But, I have done a lot of heat treating and sent a lot out to heat treaters from places I was employed at. You obviously have done neither. I followed that linc you had posted and that guy does NOT know what he is talking about. You do not have to use a salt bath to quench 4140. It will jump up to 56-58 RC in oil. 4140 will crystalize in a water quench, so I have no idea what salt slush will do to it. I have never seen any reliable source condoning the use of a salt bath for heat treating 4140.

No I am not a professional on metallurgy.
But '35-36 RC'
I know what is above is not hard even though it might be heat treated. I had an issue with a polytech M14. The Bolt was 40 rockwell and my gunsmith confirmed it. The receiver, we measured it and it was between if IIRC 55-60 that seemed be what was acceptable. I substituted a TRW bolt that was a lot harder than the chinese bolt was. I am guessing that the chinese designed that bolt to wear out. Those guns were originally being supplied to guerilla forces in the Philippines prior to being sold in the USA and to Canada.
'use of a salt bath for heat treating 4140.'
Here I just do not know. I do know that there could be a difference in heat transfer between brine and a straight water quench. But I just do not have the knowledge to comment further even if you have.

 

You do not understand "Hardness" as applied to different materials. The M-14 receiver should be made from 8620. The Chinese model, who knows? The issue with the polytech M-14 was the Chinese. I was in machining and gun repair 40+ years. I remember when the Chinese junk(Everything) came pouring in. There were a lot of guys making money reheat treating operating rods and selling new springs for those guns. In the early '90s the Chinese could not even make steel, let alone heat treat it. All that changed since US companies sent people over there to set them up. Now they do have the technology. I worked at a place that had large dealings with China. We would get tubs and tubs of simple steel spacers that were so out of spec they were unusable. The chemical analysis on some of the 1215 steel we got in was 1050. The company did not care. They got credit for the bad parts and made serious money scrapping out the parts right during the height of scrap prices.
If you want some serious reading: P.O. Ackley's "Handbook for Shooters & Reloaders"- volume II THE STRENGTH OF MILITARY RIFLE ACTIONS page 18. The whole section is a good read. This guy really tested rifles and did not just quote someone else.

 

The issue with the polytech M-14 was the Chinese. I was in machining and gun repair 40+ years. I remember when the Chinese junk(Everything) came pouring in. There were a lot of guys making money reheat treating operating rods and selling new springs for those guns. In the early '90s the Chinese could not even make steel, let alone heat treat it. All that changed since US companies sent people over there to set them up. Now they do have the technology. I worked at a place that had large dealings with China. We would get tubs and tubs of simple steel spacers that were so out of spec they were unusable. The chemical analysis on some of the 1215 steel we got in was 1050. The company did not care. They got credit for the bad parts and made serious money scrapping out the parts right during the height of scrap prices.
If you want some serious reading: P.O. Ackley's "Handbook for Shooters & Reloaders"- volume II THE STRENGTH OF MILITARY RIFLE ACTIONS page 18. The whole section is a good read. This guy really tested rifles and did not just quote someone else.

Thanks for the reading suggesting and it is a good suggestion.
Chinese Polytech receivers were considered to be in most cases of superior metallurgy and equivalent to a US GI receiver. What I found was their machining was not the best. The metallurgy of some parts was apparently not as good as in the example of the bolt.
The metallurgy of their SKS and AKM rifles was more then adequate for the tasks that were required.

Look I am not in the business of a gunsmith and certainly not heat treating. For the french action. The only way to know and this for extended firing is to have some way of measuring minute changes in headspace. I have no knowledge of failure of the MAS 36 and only said there was controversy over it. If I had one, i would load 308 down to the velocity spec of the original cartridge and leave it at that.

 

I found a reference (a US military report, I think it was from 1966) that makes it seem as if the North Vietnamese were rechambering MAS-36s to 7.62x54mm in the early 1960s. Here's an excerpt:

 

Interesting. I wonder whether the “Communist 7.62 round of ammunition” mentioned was the “54” Mosin round, the “39” AK round, or conceivably, but doubtfully, the 7.62x25 Tokarev or 7.62 Nagant round?

Please share the citation details on this reference, and hopefully a link.

Thanks for posting!

PS: I’ve examined quite a few Vietnam bringback MAS 36 rifles and, to the best of my knowledge and belief, I’ve never encountered one that was “refitted” to chamber Communist ammunition. I should note the possible caveat that if the conversion was performed without altering the outward appearance of the rifle, or adding some markings or other external indicators, it’s possible that I have indeed encountered such a rifle without even knowing.

 

My guess is that they meant 7.62x54, as it would have been circa 1959-1963, so too early for 7.62x39 in the war. And by "carbines" they mean the Type 53 I'm presuming.

Ian of FW also stated that he's never heard of such a thing. However, as you said, if there's no external indication of the conversion, perhaps it's gone unnoticed? Or, perhaps there were so few converted that one was never brought back to the US as a souvenir.

It's from this 1968 CIA report: https://www.cia.gov/readingroom/docs/CIA-RDP78T02095R000800070039-3.pdf

 

My guess is that they meant 7.62x54, as it would have been circa 1959-1963, so too early for 7.62x39 in the war. And by "carbines" they mean the Type 53 I'm presuming.

Ian of FW also stated that he's never heard of such a thing. However, as you said, if there's no external indication of the conversion, perhaps it's gone unnoticed? Or, perhaps there were so few converted that one was never brought back to the US as a souvenir.

It's from this 1968 CIA report: https://www.cia.gov/readingroom/docs/CIA-RDP78T02095R000800070039-3.pdf

Thanks for the link!

 

I have always heard it told that the MAS 36 action is very strong. My shoulder can't tell the diff from 7.5 to 7.62x51 with old mil bolt rifles.

 

That would make more sense. Certainly the .308 conversions were done much later by Century for domestic consumption?

 

Certainly the .308 conversions were done much later by Century for domestic consumption?

Yes.

 

I would buy an original chamber Mas 36 rifle not a chimp CAI conversion. See the near end of this ancient post .

https://www.treasurebunker.com/forums/index.php?/topic/4555-french-mas-36-pre-war-and-post-war/#comment-31037