Steel type???

[IntelGDR691]

If you compare different kind of receiver, i was told that there is big difference in the steel type used. For exemple, if you look in the brownells catalog, they tell you that the dakota action is made a of certain type of chrome moly steel, but the don't say it for the remington and the CZ.

I supposed that the remmy or CZ are made of less quality steel, Am I right or wrong? I supposes that the same thing applies for stainless steel. 'Cause i was explained by my department gunsmith that, usually (for example), a remington 700 receiver in blue steel is stronger and stiffer than his stainless steel counter part. That's why he recommend building a ''custom'' 700 on a chrome moly receiver.

So basically, can we say that a mass production receiver (rem, win, cz...) is made from a ''softer'' steel compare to a custom made (Dakota, PGW, Nesika)...?

Just wondering if it worth the price to buy a "custom" action vs. a blueprinted remington 700 action (chrome moly or S/S).....

Need the opinions of the pros out there...

 

[cosmic]

Low Alloy ( chrome moly) AISI 4140 steel is used by pretty well all current manufacturers for blued guns Its properties make it about 50 % stronger than regular steel, as far as tensile strength is concerned - this is the ability to accept stress without failing. However, the modulus of elasticity is about the same for all steels - this is the "stiffness" property.
Stainless has comparable properties, depending upon the grade, with perhaps the modulus of elasticity being a few percent less - not enough to show advantage.
I dont think that Remmy or CZ are made of less quality steel - its all very good! It has to be! Moreover, I wouldnt get too concerned about steel type affecting the stiffness or strength of a receiver - the factories design according to the properties of the material. However, it is fair to speculate that one reciever may be stiffer than another - this is achieved by engineering it to be so. For example, designs that are lowly stressed, or have a larger moment of inertia, and are manufactured to tighter tolerances...
One remaining thing - stainless has a much larger coefficient of thermal expansion than cro-mo. I'll leave others to speculate whether this phenomenon disadvantages stainless..

Bonne Chance...

 

[IntelGDR691]

Thanks man, nice answer...

 

[Mudpuppy]

The type of steel used in firearms manufacturing has more to do with costs than quality. There are many types of steel that you can use to build a firearm and they will all give you the same results/performance in the end, it's how you achieve that end and what it costs that matters to the manufacturer.

A custom maker may use a "harder" steel to manufacture their firearm because they cannot justify spending the money on heat treating equipment to treat softer steel and bring it up to the required level of "hardness'. If they are only producing a couple hundred firearms/parts a year it is probably cheaper for them to spend the money on the tooling required to cut the harder steel. So if they get 5 receivers cut from a chunk of steel per "bit" they are happy.

A large manufacturer usually has the money to buy all the equipment they need and they are looking at producing their product in the (ten) thousands. They will use the "softer" steel because they can cut more receivers per "bit". If they have to change the "bits" every 5 receivers, it slows down production and costs them money. Using the "softer" steel allows them to keep things moving along and they can then heat treat the final product in batches and bring it up to the same "hardness" as the custom made one for less per unit cost.

So in the end, both receivers perform basically the same and meet similar specs, they just took different routes to get there. The custom one may still cost a little more because it usually has the "extra" machining done to it when you buy it vs. having to get it done to the mass produced version.

 

[guntech]

Just wondering if it worth the price to buy a "custom" action vs. a blueprinted remington 700 action (chrome moly or S/S).....

That is a personal decision.

The 700 action in chrome-moly is the strongest mass produced action ever made. It is kind of amazing how a piece of fairly soft tubing has worked so well for so many years..... relatively inexpensive.

There are some very attractive customs action choices. They all tend to be considerable more money.

 

[thecollector]

cosmic and Mudpuppy have told it like it is.

a remington 700 receiver in blue steel is stronger and stiffer than his stainless steel counter part.

NO! Young's Modulus of elasticity (stiffness/ridgidity) for ALL steel alloys is within 29 to 30 million psi. The industry standard stainless steel for barrel and action fabrication is AISI 416 Martensitic Stainless; this stainless alloy is heat treatable and can be quenched and tempered to any hardness/strength level as AISI 4100 series chromium molybdenum steels can.

 

[Rapt]

Hold on! Just because its hardenable doesn't mean its hardenable to any level, NOR does it mean it is hardened to its peak potential just because its been heat treated.

Generally speaking stainless is softer and doesn't move on itself as smoothly as comparable HSLA steels. Its wears faster too. They make critical aircraft parts of 4140 or 4340, not 416 for a reason.

Another general observation is most gun parts are heat treated and tempered to levels well below their maximum since softer steel fails in yield and results in stretched and bent bits when failure happens. Harder steel fails in fracture and tends to just go "bang" without warning.

Usually this is considered a bad thing in a firearm.

 

[thecollector]

Out of the five categories of stainless steels:
1) Ferritic
2) Austenitic
3) Martensitic
4) Precipitation Hardenable
5) Duplex
only the heat treatable Martensitic and Precipitaton Hardenable types are suitable for firearms fabrication of barrels and actions.

NOR does it mean it is hardened to its peak potential just because its been heat treated. Another general observation is most gun parts are heat treated and tempered to levels well below their maximum

This is quite correct. AISI 4140 chromium molybdenum steel (the ubiqutous barrel and action HLSA [high strength low alloy steel]) is generaly quenched and tempered to the 120,000 to 140,000 psi tensile yield strength range for rifle applications. 4140 steel is capable of being heat treated up to 220,000 psi yield strength, but in this condition it is far to BRITTLE for the impact loading dynamics of firearms applications; so an engineering balance (by design) is struck between between required yield strength and impact (high rate load application) resistance.

They make critical aircraft parts of 4140 or 4340, not 416 for a reason.

Correct again. Structural aircraft components have quite different performance/materials requirements than firearms barrel and action requirements. 416 is a resulfurized heat treatable martensitic stainless steel employed for 'thick walled cylinder' (ie. barrel applications) where strength to weight ratio is not a primary design parameter; the resulfurization of 416 stainless intentionaly results in sulfur 'stringers' within this steel which vastly increases its machineability, and hence profitability. Barrels and actions are designed with generous safety margins by adding material section thickness. This 'material section thickness' (weight addition) method of safety factor attainment is not acceptable in the areo-space industry for obvious reasons. The 'thin wall' requirements of areo-space applications is not suited to resulfurized alloys; the 'clean' HSLA steels such as 4100 series and 4300 series nickel, chromium, molybdenum steels meet the engineering requirements of sturctural aircraft components much better than the stainless group of steels, with the exception of the precipitation hardenable stainless alloys, not to mention the titainium group of alloys, and the Inconel, et al group of super alloys.

Now that I have anethetized every one's brain that read this far........I better f**k off........cheers gents.

 

[thecollector]

Out of the five categories of stainless steels:
1) Ferritic
2) Austenitic
3) Martensitic
4) Precipitation Hardenable
5) Duplex
only the heat treatable Martensitic and Precipitaton Hardenable types are suitable for firearms fabrication of barrels and actions.

NOR does it mean it is hardened to its peak potential just because its been heat treated. Another general observation is most gun parts are heat treated and tempered to levels well below their maximum

This is quite correct. AISI 4140 chromium molybdenum steel (the ubiqutous barrel and action HLSA [high strength low alloy steel]) is generaly quenched and tempered to the 120,000 to 140,000 psi tensile yield strength range for rifle applications. 4140 steel is capable of being heat treated up to 220,000 psi yield strength, but in this condition it is far to BRITTLE for the impact loading dynamics of firearms applications; so an engineering balance (by design) is struck between between required yield strength and impact (high rate load application) resistance.

They make critical aircraft parts of 4140 or 4340, not 416 for a reason.

Correct again. Structural aricraft components have quite different performance/materials requirements than firearms barrel and action requirements. 416 is a resulfurized heat treatable martensitic stainless steel employed for 'thick walled cylinder' (ie. barrel applications) where strength to weight ratio is not a primary design parameter; the resulfurization of 416 stainless intentionaly results in sulfur 'stringers' within this steel which vastly increases its machineability, and hence profitability. Barrels and actions are designed with generous safety margins by adding material section thickness. This 'material section thickness' (weight addition) method of safety factor is not acceptable in the areo-space industry for obvious reasons. The 'thin wall' requirements of areo-space applications is not suited to resulfurized alloys; the 'clean' HSLA steels such as 4100 series and 4300 series nickel, chromium, molybdenum steels meet the engineering requirements of sturctural aircraft components much better than the stainless group of steels, with the exception of the precipitation hardenable stainless alloys, not to mention the titainium group of alloys, and the Inconel, et al group of super alloys.

Now that I have anethetized every one's brain that read this far........I better #### off........cheers gents.

 

[thecollector]

Woops for the double tap..........I am at the bottom of the wine bottle now.

 

[cosmic]

Interesting thread - Metallurgy is a complex field.... Early in the last century, there were several examples of generic firearm failures induced by incorrect heat treatment, or faulty material specification. There were even ships that disappeared mysteriously because of catastrophic failure of their all welded hulls hitting the nil ductility temperature in frigid North Atlantic waters....
Its interesting to note that firearm components are very highly stressed, compared to other engineered components (such as pressure vessels). A few years ago, I calculated the hoop stresses in a Lee Enfield chamber using the Lame equations for thickwall cylinders, and came up with values in the order of 70,000 psi! (ie factor of safety of approx 1.5...) This doesnt compare well with typical factors of safety of approx 3 in engineered components!
Ever since then, I reload to minimum specs

 

[thecollector]

Interesting thread - Metallurgy is a complex field

An understatement indeed.

catastrophic failure of their all welded hulls hitting the nil ductility temperature in frigid North Atlantic waters....

Yep, the ductile to brittle transition failure temp is not far from room temp for most steel alloys. High nickel content steel alloys (such as austenitic stainless and the nickel super alloys) are fine for cryogenic temp service.

A few years ago, I calculated the hoop stresses in a Lee Enfield chamber using the Lame equations for thickwall cylinders, and came up with values in the order of 70,000 psi!

Yep, run your Lame's equation calcs again using variable wall thicknesses and you will see that the tangental, and shear stress components at any radial displacement are a function of wall thickness..........cool ####!

 

[Hitzy]

The Swiss used Crome Nickle steel for their K31's from the 30's to the 50's. They did use Crome Moly for one year (1944) due to supply shortages, and went back to CN.
Is CN too expensive these days to make receivers from?

 

[IntelGDR691]

Hummm, very interesting guys, but i'm not sure i can follow you on that... So basically, stainless steel or chrome moly receiver....? (winchester, remington...)

 

[cosmic]

OK Intel... - You are ordered to use a Remington Chrome Moly action!

Hitzy - Difficult to answer your question. Metallurgy evolved tremendously at the turn of the last century. When it was established that steel with a threshold carbon content could be enhanced by heat treatment, a wealth of applications were tried.
However, it was realized that using carbon as the sole alloying element had limits - proper quenching was hard to achieve. With the addition of small percentages of chrome, nickel, and molybdenum, more consistent heat treatment was achieved. Today various combinations exist Ni, Ni-Cr, Ni-Cr-Mo, Cr-Mo, Ni-Mo. (AISI 3140 is a Ni-Cr steel with comparable properties to Cr-Mo 4140.)
To compound matters there are also steels called HSLA (High Strength Low Alloy) that use nickel, chromium, moly, and vanadium without heat treatment.

Nickel alloy steels have a history of use in modern arms manufacture. Nickel steel was utilized in the Springfield rifle after carbon steel was determined to be problematic, as described above. Also, I believe commercial rifles such as Win 1895's utilized nickel steels.
I suspect the Swiss resorted to Cr-Mo steels for the reasons you mention - war induced supply constraints. Nickel is used extensively in stainless steel, and copper nickel alloys for marine service.

 

[tiriaq]

Apart from the great knowledge that has been amassed about steel alloys and their properties, there remains the issue of controlled, consistant manufacture and processing of the desired alloy at a quality level satisfactory for the desired purpose. Look at the recent failures involving supposedly high quality target rifle barrels in Australia.

 

[thecollector]

Look at the recent failures involving supposedly high quality target rifle barrels in Australia.

Tiriag, would you have a link for that, I would be quite interested in reading about it.

More metalurgy; the primary alloying elements Mn, Ni, Cr, Mo, and V for alloy steel fabrication, work their magic by increasing the depth of hardenability for any given quench rate. A prime example are rifle barrel billets, they must be strengthened to the centre of the billet; a large plain carbon steel billet upon quenching, would have a hardened exterior with a relatively softer and weaker interior (no good for building barrels as the greatest stresses on firing occur at the inner chamber wall). These alloying elements also permit a less severe quench while still attaining proper hardenability depth; this is very important as severe water or oil quenches can produce large distortions and even cracking in the work piece, resulting in scrap. In moderate section thicknesses, alloys such as 4300 series Ni-Cr-Mo steels can even be gas quenched in argon, nitrogen, or air, attaining full depth hardenability.

Then we have the tool steels which contain higher levels of the formentioned elements, with more carbon, and can also include Cobalt and Tungsten; these high speed tool steels will retain their strength and hardness at red heat working temperatures necessary for high feed cutting rates to minimize machining times and maximize profitability.

 

[tiriaq]

There should be information about the barrel problems at www.dcra.ca, www.long-range.com. As well there should be a link at dcra to the Australian Rifle Ass'n. Pretty scary failure.