Metallurgical Test On Mosin Nagant Bolts

[jackieschmidt]

A few weeks ago, we had a good discussion about Mosin Nagant rifles.
As with any discussions surrounding vintage military rifles, the question of strength came up. This leads to a discussion about materials, heat treating, etc.There were quite a few opinions.

But, as with many opinions, there were a lot of “I have heard”, “a friend said”, “it’s been reported”, none based on any facts.

So I asked if anyone had a Mosin bolt they could send me, I would take it over to the testing lab we use and find out what the steel is, the hardness, and once that is known, the strength level.

Mike at Tier One sent me two bolt heads, I took them to W H laboratories. Here are the reports.

As you can see, even though the bolts look identical, there is a big difference in the material, and the heat treat as measured by the RC number.

Bolt A is 1060 carbon steel. The bolt measured 60+ RC even at the core. This leads me to believe that the bolt was hardened, but there was never an appreciable temper draw.

Bolt B is 1049 carbon steel. The RC number shows that it went through a standard quenching followed by a temper draw to bring the RC number to the low 40’s.

From my knowledge of metallurgy and ideal strength combinations of tensile and yield strength combined with ductility, bolt A is far too hard. Too hard to the extent that ductility is severely compromised. Bolt B however is at an ideal RC number to give a good combination of tensile and yield strength while maintaining good ductility.
Bolt A is from the Izhevsk factory, bolt B from the Tula factory.

Here are the results including a heat treat chart for similar steels.

Carbon steels were very common in the manufacture of many country’s firearms. Alloy steels such as 4140 only came into vogue post WW-2.

You can study them and draw your own conclusions based on the numbers,

 

[jackieschmidt]

A few weeks ago, we had a good discussion about Mosin Nagant rifles.
As with any discussions surrounding vintage military rifles, the question of strength came up. This leads to a discussion about materials, heat treating, etc.There were quite a few opinions.

But, as with many opinions, there were a lot of “I have heard”, “a friend said”, “it’s been reported”, none based on any facts.

So I asked if anyone had a Mosin bolt they could send me, I would take it over to the testing lab we use and find out what the steel is, the harness, and once that is known, the strength level.

Mike at Tier One sent me two bolt heads, I took them to W H laboratories. Here are the reports.

As you can see, even though the bolts look identical, there is a big difference in the material, and the heat treat as measured by the RC number.

Bolt A is 1060 carbon steel. The bolt measured 60+ RC even at the core. This leads me to believe that the bolt was hardened, but there was no appreciable temper draw.

Bolt B is 1049 carbon steel. The RC number shows that it went through a standard quenching followed by a temper draw to bring the RC number to the low 40’s.

From my knowledge of metallurgy and ideal strength combinations of tensile and yield strength combined with ductility, bolt A is way too hard. Too hard to the extent that ductility is severely compromised. Bolt B however is at an ideal RC number to give a good combination of tensile and yield strength while maintaining good ductility.

Here are the results including a heat treat chart for similar steels.

You can study them and draw your own conclusions based on the numbers,View attachment 1428820View attachment 1428821View attachment 1428821View attachment 1428822View attachment 1428823View attachment 1428824View attachment 1428825

As you can see by the first chart, (similar to bolt A), the tensile and yield strengths are off the chart at that 60+ RC, but ductility is just about non existent.

It the second charts (similar to bolt B), you have close to 150,000 tensile and around 100,000 yield with enough retained ductility to avoid stress fractures and failure.

 

[Twdmar]

Neat!

 

[Alan Warner]

A few weeks ago, we had a good discussion about Mosin Nagant rifles.
As with any discussions surrounding vintage military rifles, the question of strength came up. This leads to a discussion about materials, heat treating, etc.There were quite a few opinions.

But, as with many opinions, there were a lot of “I have heard”, “a friend said”, “it’s been reported”, none based on any facts.

So I asked if anyone had a Mosin bolt they could send me, I would take it over to the testing lab we use and find out what the steel is, the hardness, and once that is known, the strength level.

Mike at Tier One sent me two bolt heads, I took them to W H laboratories. Here are the reports.

As you can see, even though the bolts look identical, there is a big difference in the material, and the heat treat as measured by the RC number.

Bolt A is 1060 carbon steel. The bolt measured 60+ RC even at the core. This leads me to believe that the bolt was hardened, but there was never an appreciable temper draw.

Bolt B is 1049 carbon steel. The RC number shows that it went through a standard quenching followed by a temper draw to bring the RC number to the low 40’s.

From my knowledge of metallurgy and ideal strength combinations of tensile and yield strength combined with ductility, bolt A is far too hard. Too hard to the extent that ductility is severely compromised. Bolt B however is at an ideal RC number to give a good combination of tensile and yield strength while maintaining good ductility.
Bolt A is from the Izhevsk factory, bolt B from the Tula factory.

Here are the results including a heat treat chart for similar steels.

Carbon steels were very common in the manufacture of many country’s firearms. Alloy steels such as 4140 only came into vogue post WW-2.

You can study them and draw your own conclusions based on the numbers,View attachment 1428820View attachment 1428821View attachment 1428821View attachment 1428822to of pre

Nice work Jackie. Not often this work is done. You will find similar wide variations in lots of pre 64 Winchester also. That's one reason I quit working them.

 

[LVLAaron]

I used to work for a Metallurgy lab. I sure let that time go to waste.


What book are you referencing there?

 

[jackieschmidt]

I went over and got the bolt Heads back from the Lab, here they are. You can see what is involved it ascertaining this information.

If anybody is interested in what it cost to get this done, $450.

I hope this answers a few questions about these. I was hoping to have a discussion, especially the notable difference in the two bolt heads from a different manufacturer, and possibly a different era.

I would like to do an action body as well. Not sure I want to spend another $450, but if a Tula action is similar in material and RC hardness as the “B” bolt head, this should be fine for any cartridge loaded to factory specs in the 50 to 55,000 psi range.

The “A” ? I have my doubts considering the very high carbon content and the RC hardness.

 

[AlNyhus]

Jackie, once again you step up to the plate with your time and resources to get an answer.

Sometimes, the learning is the best part of the journey. The Waiting...not so much.

 

[tobnpr]

Fascinating stuff, Jackie- saw your PM this morning but didn't have time to give you a call.

My "gut" told me that the Tula metallurgy would be superior to that of Izhevsk- but that's strictly anecdotal and based on the quality of the chambers and the machining of the barrels themselves. Anyone that's purchased a MN in the last couple of decades (since the days when a sealed crate of refurbs from the armory was under a grand) knows that the rifles produced by the Tula factory command a premium, not as much as the Finnish rifles- but more nonetheless due to better overall quality. Same goes for other Tula-produced firearms such as SKS's and AK's- they carry a price premium.

There used to be a website (7.62x54r.net) that recently went bye-bye. Quite a shame, it had mountains of specs- including estimated production by year from each factory. The Izhevsk factory by far had the greatest production numbers- especially during WWII. Literally millions of them in 1943, and it's obvious from the machining on the barrels and receivers that they were cranked out as fast as the production lines could handle with no regard to cosmetic quality as one would expect. This is a 1943 Izhevsk barrel- all of the machining artifacts plainly visible as they couldn't have cared less about "feeds and speeds"- and one can plainly feel bumps all up and down the barrel from ripping that metal off as fast as possible from a skinny pencil barrel. In fairness to Izhevsk, the pre-war (WWII, that is...) are of better quality.

Here, is a 1936 Tula:

What's "unknowable" is the date of production of the boltheads. I used to buy boxes and boxes of these parts from Sarco back when they were dirt cheap, so I have an abundance of them. But being undated, no way to know when they were produced. The bolt bodies were serialized, and the receivers were usually (but not always) production dated on the bottom of the tang. If one has an all numbers-matching rifle, it would be "probably" safe to assume the bolthead is original to that rifle- but no guarantee. With the floating bolthead design, they were often replaced/swapped (especially in arsenal refurbs) to adjust headspace- and I frequently do this myself with customers' rifles.

The Izhevsk bolthead- lacking proper temper- would seem to fit wartime production and "shortcuts" to get them out the door. It's well documented with Mausers, that wartime production K98k's are to be avoided for modern, higher pressure cartridge conversions. With MN's, I prefer the pre-war hex receivers and have no trepidation rebarreling them into 55-60 Kpsi chamberings. For anyone that cares to dig up some history, the Bannerman company in the 1920s rechambered thousands of surplus MN's (many of them U.S. made by New England Westinghouse and Remington- did ya know that ) in 30-.06.

The conversion was deemed "unsafe", as Bannerman simply lopped off the tenon, cut a new one with the 30-.06 chamber. This placed the forward part of the chamber ahead of the cylinder and into the skinny part of the barrel just behind the rear sight. Many still shoot them, but personally I'd shy away from them- not because of the 30-.06 as I've done quite a few of them- but because of the way it was done back then.

Awesome of you to have done this, Jackie. While much has been done with Mausers, I've not seen this done before with the Mosin-Nagant, despite it having higher production numbers (over 35 million) than any other rifle in history far as I know. Now, we can wonder how the U.S. made parts stack up

 

[jackieschmidt]

The one thing that was unexpected in the report was niether bolt was “case hardenned”, as we define it. I surely thought bolt “A” would be, since I could not scratch it with a file. I expected a case hardening with a properly treated core.

I talked to the Metallurgist today, and he agreed with my assessment. They simply quenched the darn thing, and skipped the tempering phase. That is the only way the bolt could have ended up at 60RC all the way to the core.

Before i got into this, all I knew about these rifles was what I had read. I will inject my opinion here.

I think the basic design of the bolt is pretty good. The way the extractor is attached leaves it very robust. No pins, no springs, it looks 100% efficient. And, it is a floating bolt head.

The way the bolt head attaches and is held on the bolt body forgoes any pin or hole drilled through the bolt body. When you look at the myriad of machining operations your first thought is….”they had a basic design and just kept setting up operations until someone declared it‘s finished”.

I still stand by my statement that if an action body of the Tula, or any other for that matter, matches the material and RC hardness of the Tula bolt, there is no reason it should not be a sound platform for a modern cartridge.

If you could come across a Tula body, I would be interested in having the metallurgy done. The logistics is more complicated, seeing that you cannot ship an action body unless a FFL is involved.

And then there is the fact it would cost more to do the metallurgy than the thing is worth.

But I sure would like to know what steel the action bodies were machined from.

 

[762plinker]

A

The one thing that was unexpected in the report was niether bolt was “case hardenned”, as we define it. I surely thought bolt “A” would be, since I could not scratch it with a file. I expected a case hardening with a properly treated core.

I talked to the Metallurgist today, and he agreed with my assessment. They simply quenched the darn thing, and skipped the tempering phase. That is the only way the bolt could have ended up at 60RC all the way to the core.

Before i got into this, all I knew about these rifles was what I had read. I will inject my opinion here.

I think the basic design of the bolt is pretty good. The way the extractor is attached leaves it very robust. No pins, no springs, it looks 100% efficient. And, it is a floating bolt head.

The way the bolt head attaches and is held on the bolt body forgoes any pin or hole drilled through the bolt body. When you look at the myriad of machining operations your first thought is….”they had a basic design and just kept setting up operations until someone declared it‘s finished”.

I still stand by my statement that if an action body of the Tula, or any other for that matter, matches the material and RC hardness of the Tula bolt, there is no reason it should not be a sound platform for a modern cartridge.

If you could come across a Tula body, I would be interested in having the metallurgy done. The logistics is more complicated, seeing that you cannot ship an action body unless a FFL is involved.

And then there is the fact it would cost more to do the metallurgy than the thing is worth.

But I sure would like to know what steel the action bodies were machined from.

VERY GOOD 91/30 IS ABOUT $560 AND A GREAT IS 585.....MY LIKE NEW IS MORE LIKE 600..( THERE IS A SOFTWARE TOOL THE SURVEYS ACTUAL SALES OF LOTS OF MIL SURPLUS RIFLES)

 

[jackieschmidt]

A

VERY GOOD 91/30 IS ABOUT $560 AND A GREAT IS 585.....MY LIKE NEW IS MORE LIKE 600..( THERE IS A SOFTWARE TOOL THE SURVEYS ACTUAL SALES OF LOTS OF MIL SURPLUS RIFLES)

If you are looking for a Mosin to build a Mosin Nagant custom, the only thing I would be interested in is what we discovered in the metallurgical analysis. That being, the metallurgical aspects of critical action components.

A Rockwell C test is the only 100% way to ascertain this. If one understands the concept, you can simply do a scratch test. If a file skates over the part with no noticeable mark, you can be reasonably sure that the part did not undergo a hardening cycle followed by a proper drawing of the temper in order to achieve the proper mechanical properties.

The fact that two random bolt heads from two different manufacturing facilities showed a wide degree of variance in material and heat treat would compel me to take a pause.

All of the other parameters of how Gun Brokers rate rifles are useless if the intended purpose is to base a custom on the action. The only thing that counts is the metallurgy of the stressed parts.

In short, if you have a Molsin that exhibits the same characteristics as bolt “A”, I would not use it in any application that exceeds the operating pressure of the original 7.62x54 R cartridge.

 

[jackieschmidt]

I used to work for a Metallurgy lab. I sure let that time go to waste.


What book are you referencing there?

The charts are from the Jorgensen Steel Engineering section.

There are multitudes of graphs tracking the various mechanical properties of steel, these are easy to read and diagnose, especially in the realm of how ductility relates to RC hardness levels.

 

[X Count]

In the battle of Stalingrad the average lifespan of a soldier was 24hrs. Something like 470,000 died and 650,000 injured.

They were sending soldiers forward without rifles to pick up off the dead. In that situation I'd probably be happy to be given a gun, bayonet and 5 rounds even if the bolt was 60rc and had a rough finish on the barrel!

 

[Sniperhandle]

The one thing that was unexpected in the report was niether bolt was “case hardenned”, as we define it. I surely thought bolt “A” would be, since I could not scratch it with a file. I expected a case hardening with a properly treated core.

I talked to the Metallurgist today, and he agreed with my assessment. They simply quenched the darn thing, and skipped the tempering phase. That is the only way the bolt could have ended up at 60RC all the way to the core.

Before i got into this, all I knew about these rifles was what I had read. I will inject my opinion here.

I think the basic design of the bolt is pretty good. The way the extractor is attached leaves it very robust. No pins, no springs, it looks 100% efficient. And, it is a floating bolt head.

The way the bolt head attaches and is held on the bolt body forgoes any pin or hole drilled through the bolt body. When you look at the myriad of machining operations your first thought is….”they had a basic design and just kept setting up operations until someone declared it‘s finished”.

I still stand by my statement that if an action body of the Tula, or any other for that matter, matches the material and RC hardness of the Tula bolt, there is no reason it should not be a sound platform for a modern cartridge.

If you could come across a Tula body, I would be interested in having the metallurgy done. The logistics is more complicated, seeing that you cannot ship an action body unless a FFL is involved.

And then there is the fact it would cost more to do the metallurgy than the thing is worth.

But I sure would like to know what steel the action bodies were machined from.

You could cut the action into 3 peices and then it is demilled and no need to worry about shipping issues.

Very cool you did this testing, I would have bet these were case hardened like Mausers, Who'd have thunk?

 

[davidjoe]

Is it the imprinted Star that determines the originating factory?

 

[Sniperhandle]

Is it the imprinted Star that determines the originating factory?

That is a Tula

 

[tobnpr]

If you could come across a Tula body, I would be interested in having the metallurgy done. The logistics is more complicated, seeing that you cannot ship an action body unless a FFL is involved.

I've got maybe a half-dozen stripped receivers somewhere in the back of a safe that I bought from Copes six or seven years ago before they closed their doors- I'll check to see if any are Tula; if so- I can de-mill and ship as suggested. Spot-on with the complicated machining ops- damned if I can figure out how they did them, but I don't consider myself a true "machinist".

I was contacted by Criterion barrels close to a decade ago, they were considering making replacement barrels in original configuration. Kicked it around for a bit- and in the end nixed the idea because of the difficulty in machining the rear sight dovetail, and front sight post (at a price point, anyway). When I look at the bolt body itself- crazy. No idea how they did it, especially on the machinery available 125 years ago.

Far as overall design of the receiver, the split-bridge sucks for scope mounts but Rock Solid has had an excellent design for many years that's bulletproof and solves that issue. Or, you can get creative as Sniperhandle has done and weld-up that area (a piece of a demilled receiver is perfect). Move the bolt handle back closer to the tang where it's more ergonomic and voila...

While the split bridge is a negative for scope mounts- it's a huge plus IMO for the strength of the lugs/abutments. Rather than 12:00 and 6:00, they're at 3:00 and 9:00. The entire left side of the receiver is the lug abutment, and on the right side- there's a significant shelf for the lug itself, and the bolt body itself serves as a "safety lug" against the back sidewall of the receiver. Way over-designed for it's era.

I've seen video where a guy filled the case with Bullseye- topped it with a boolit and pulled the trigger (remotely with a looong string, natch). Several minutes later after pounding the bolt handle with a mallet he broke it loose. Not that I'd ever use it after that- but the receiver survived. There are cases where the receivers have failed, but they're very rare.

I had one sent in some years ago for Cerakote and some other work. After blasting with AlOx prior to coating- I noticed a very faint hairline crack that extended from the bottom edge of the receiver ring into the recoil block. Had I not blasted it, I'd never have seen it. The customer had just purchased it, hadn't fired it and didn't know any of it's history- but I suspect it was due to over-torquing when the barrel was installed. Needless to say I refit his barrel to a "new" receiver, but that's the only receiver I've encountered out of hundreds of them that had an issue.

I've had so many nay sayers over the years with the "putting lipstick on a pig" line that I just ignore them.
The receivers are solid, and the 54r is the longest serving round in active military duty in history- and still going strong for a reason. Even now, still widely used in Europe as a hunting round- easily matches .308 performance, and handloaders can get velocities approaching 30-.06.

 

[jackieschmidt]

I've got maybe a half-dozen stripped receivers somewhere in the back of a safe that I bought from Copes six or seven years ago before they closed their doors- I'll check to see if any are Tula; if so- I can de-mill and ship as suggested. Spot-on with the complicated machining ops- damned if I can figure out how they did them, but I don't consider myself a true "machinist".

I was contacted by Criterion barrels close to a decade ago, they were considering making replacement barrels in original configuration. Kicked it around for a bit- and in the end nixed the idea because of the difficulty in machining the rear sight dovetail, and front sight post (at a price point, anyway). When I look at the bolt body itself- crazy. No idea how they did it, especially on the machinery available 125 years ago.

Far as overall design of the receiver, the split-bridge sucks for scope mounts but Rock Solid has had an excellent design for many years that's bulletproof and solves that issue. Or, you can get creative as Sniperhandle has done and weld-up that area (a piece of a demilled receiver is perfect). Move the bolt handle back closer to the tang where it's more ergonomic and voila...

While the split bridge is a negative for scope mounts- it's a huge plus IMO for the strength of the lugs/abutments. Rather than 12:00 and 6:00, they're at 3:00 and 9:00. The entire left side of the receiver is the lug abutment, and on the right side- there's a significant shelf for the lug itself, and the bolt body itself serves as a "safety lug" against the back sidewall of the receiver. Way over-designed for it's era.

I've seen video where a guy filled the case with Bullseye- topped it with a boolit and pulled the trigger (remotely with a looong string, natch). Several minutes later after pounding the bolt handle with a mallet he broke it loose. Not that I'd ever use it after that- but the receiver survived. There are cases where the receivers have failed, but they're very rare.

I had one sent in some years ago for Cerakote and some other work. After blasting with AlOx prior to coating- I noticed a very faint hairline crack that extended from the bottom edge of the receiver ring into the recoil block. Had I not blasted it, I'd never have seen it. The customer had just purchased it, hadn't fired it and didn't know any of it's history- but I suspect it was due to over-torquing when the barrel was installed. Needless to say I refit his barrel to a "new" receiver, but that's the only receiver I've encountered out of hundreds of them that had an issue.

I've had so many nay sayers over the years with the "putting lipstick on a pig" line that I just ignore them.
The receivers are solid, and the 54r is the longest serving round in active military duty in history- and still going strong for a reason. Even now, still widely used in Europe as a hunting round- easily matches .308 performance, and handloaders can get velocities approaching 30-.06.

All of a receiver I would need is the front part that takes all of the pressure.