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The thread that caused the Forged Vs. Cast discussion to be banned from this board

47K views 106 replies 37 participants last post by  tonyben 
#1 ·
Original Title was "If a forged reciever is better... "

Why isn't anyone else doing it? LRB is pulling it off. Why don't we see anyone else offering a forged reciever.

You'd think that with the resurgence of the M14 in the military it would be profitable for companie to tool up and get started.

It would be nice to see USGI quality parts come back too.
 
#52 ·
7.62bthp, you'll ruin a perfectly good statement with facts like that.

Jose, the United States had factories already in existence with equipment capable of producing forgings by literally the thousands every day. They needed them. This was in 1940-41. By the time that the ArmaSteel project bore fruit, the production lines were up and producing. Shutting them down for the length of time required to locate and install new equipment, and bring it on line, wasn't something that the powers that be wanted to do. We had, in 1943 begun to achieve some forward momentum. It wasn't going to be allowed to slow while the military retooled it's weapons.

As for the forgings of the M14, they were built as a development/evolution of the M1 Garand. The initial units were modified Garands. There was a limited budget, and the existing military armories weren't going to be able to invest in the new technology. It's one of the reasons, budget, that M14 rifles were adopted in 1957, but didn't reach any real production levels until 1959.

Armasteel worked, as there are quite a few 1918A2 BARs out there today. It was primitive in comparison with investment casting technology of today, though. Forging technology has changed little since the nineteenth century. Since Ruger pushed the new technology in firearms manufacturing, it has gained a lot of acceptance,and for good reason.

Forging steel still works, but there are alternatives today.

Why do so many militaries still use forgings? There are different materials involved. Many of what are called forgings are actually billet machined , or bar stock machined. That's not forged parts. There are a lot of countries out here that simply don't have access to the technology necessary to equal America's investment casting abilities. The technology of forging is old, but the technology of machining is ancient.

Besides, most foreign countries are using stampings and polymers today. GI1
 
#53 ·
What Me? Ruin what statement? LOL

AKs and H&Ks are stamped, no? UZIs? Glocks and SIGs are extruded. All world class in their own way.

Forging is nice, and I paid dearly for my LRB. MODERN castings are good with me. BTW, there are some poor Forged products out there from time to time.

This is the same cast vs forged thread that pops up once a quarter. Dead horse. History has dealt it's blows. We ended up with what we got. I know, some of it don't make a lick of sense.

Tell ya what boys, if I win the 260mil dollar lottery, we'll forge a few receivers with our own private label! Jose, we'll cast ONE out of ArmaSteel for you!(JR will drool over it!) LOLDI2

Punching out! Eject! Eject! Eject!DI5
 
#54 ·
7.62bthp said:
What Me? Ruin what statement? LOL

AKs and H&Ks are stamped, no? UZIs? Glocks and SIGs are extruded. All world class in their own way.

Forging is nice, and I paid dearly for my LRB. MODERN castings are good with me. BTW, there are some poor Forged products out there from time to time.

This is the same cast vs forged thread that pops up once a quarter. Dead horse. History has dealt it's blows. We ended up with what we got. I know, some of it don't make a lick of sense.

Tell ya what boys, if I win the 260mil dollar lottery, we'll forge a few receivers with our own private label! Jose, we'll cast ONE out of ArmaSteel for you!(JR will drool over it!) LOLDI2

Punching out! Eject! Eject! Eject!DI5

Sig's and UZI's are stamped steel as AK's and HK's are. I'm not sure about Glock's. There very durable receivers though from what I've seen and enjoyed in my own PTR91, but I think a quality cast M14 receiver would take alot more abuse than any of them and not even be fazed.

I know I could probably jump up and down on my M1A receiver all day and probably only scuff the finish were if I did that to my PTR it would bend in, in no time flat.
Does that make any of them a bad choice, no, but a good cast M14 receiver is one hell of a tough receiver.
 
#55 · (Edited)
JR said:
7.62bthp, you'll ruin a perfectly good statement with facts like that.

Jose, the United States had factories already in existence with equipment capable of producing forgings by literally the thousands every day. They needed them. This was in 1940-41. By the time that the ArmaSteel project bore fruit, the production lines were up and producing. Shutting them down for the length of time required to locate and install new equipment, and bring it on line, wasn't something that the powers that be wanted to do. We had, in 1943 begun to achieve some forward momentum. It wasn't going to be allowed to slow while the military retooled it's weapons.

As for the forgings of the M14, they were built as a development/evolution of the M1 Garand. The initial units were modified Garands. There was a limited budget, and the existing military armories weren't going to be able to invest in the new technology. It's one of the reasons, budget, that M14 rifles were adopted in 1957, but didn't reach any real production levels until 1959.
JR, I am aware of the history of WWII, WPO issues with materials etc. Again, I don't want to beat a dead horse but we have conflicting ideaology here.

ArmaSteel was brought on line to have a portable "SAW" if you will in the BAR because as you stated they needed them NOW. The technology was there to make the M14 out of castings. Simpler, cheaper, and quicker is the argument made in favor. Just becaue it was an "evolution" of the Garand doesn't mean it was going to or had to be made in the same fashion.

Budget is always a concern but there was much more to the production delays of the M14. Design issues, specification issues, manufacturing issues, four manufacturers not on the same page, etc. etc.


JR said:
Armasteel worked, as there are quite a few 1918A2 BARs out there today. It was primitive in comparison with investment casting technology of today, though. Forging technology has changed little since the nineteenth century. Since Ruger pushed the new technology in firearms manufacturing, it has gained a lot of acceptance,and for good reason.
I will defer to my previous statement and I don't think anyone could come up with a casting of another military weapon of significance. The reason is there aren't any and there is a reason for that.

Steel stampings not castings replaced machined forgings. A classic evolution is the MP38/MP38-40/MP40. Another example is the evolution of the AK47. Castings are a thing of the past IMO except for the SAI M1A. Granted Ruger cast much of their stuff but, who cares?


JR said:
Forging steel still works, but there are alternatives today.

Other than stampings and plastic, I don't know of a substitute for forging.

JR said:
Why do so many militaries still use forgings? There are different materials involved. Many of what are called forgings are actually billet machined , or bar stock machined. That's not forged parts. There are a lot of countries out here that simply don't have access to the technology necessary to equal America's investment casting abilities. The technology of forging is old, but the technology of machining is ancient.

Besides, most foreign countries are using stampings and polymers today. GI1
Could you give some examples of machined billet weapons both foreign and domestic?
 
#56 ·
I was talking about generalizations. There are any number of automotive "forgings" that are machined billets. I believe that it was also brought out that one of the earlier manufacturers "forged" receivers were actually machined from bar stock. How does one produce bar stock? By the way, a couple of the smaller AR companies are supposedly maching lower receivers out of bar-stock aluminum.

Your comment about other means of producing firearms already shows your bias. Investment casting is another viable method.

If castings are a thing of the past for firearms, why are so many small parts, even in military weapons, cast? Why would you dismiss Ruger's weapons? They are the largest manufacturer of weapons in the United States. Several thousands of their KP95 pistols have already been accepted by the Automotive Tank Command, and are in-country in Iraq. Ruger's rifles and pistols are the benchmark in durability in commercial weapons. I'd say that the majority of America cares, even if you don't. Otherwise, they wouldn't sell so much, nor enjoy the reputation for durability that they have.

The military still uses any number of castings for major, and critical parts of systems. Armor plate is cast, ceramics are cast. What process does injection molding most resemble, casting or forging? What is it an outgrowth of?

Casting is used in any number of other weapons, from frames and slides, to shrouds and sights. In all too many cases, forging is what's dying away.

As for the reasoning that led to the M14 being forged, I don't believe that it was an anti-cast bent at all. The men in charge of the rifle were simply not worried about changing materials. After all, "we know that this will work", is a simple reason given by many, instead of thinking. What's the reason some people buy a Ford? "My dad had one" is something often heard, in lieu of true research. Unless you know someone from the team, you're guessing as much as to the sequence of events as anyone else is.

Your discussion of delays does more to bear out what I said than it does to disprove it.

Just for the sake of injecting logic into the discussion. The M1A cast receiver, by Sa, Armscorp, et al, was to allow them to be built economically. It wasn't a military venture. After over 20 years of service, I'd be guessing that the receivers have proven themselves as far as reliability and durability go. No, the government didn't use casting, but the success of the cast receivers, some of which are now in government service, is a telling point.

Armasteel was not brought on line to have anything NOW. It wasn't developed until 1943. The use of Armasteel was only allowed in the case of existing contracts having beem filled, and new ones issued. The 1918A2 was a time intensive process, much like the Thompson, and limited facilities were available for their production. Accordingly, the ability to speed production by a factor of six was deemed efficient. Garands, and Carbines were another matter. There had been no research done as to what mods would be needed to use Armasteel. This would have had to been done prior to the change-over, as well as the casting facilities produced and brought on line. Current casting production was already being utilized in the production of armor, artillery, and other critical efforts. If you really think that the military will change from the tried-and-true to a new technology in the middle of a maximum effort, you're delusional.

This has zero to do with the strength of a forging. That is the ONE thing in favor of an antiquated process. Even at that, it's a dying attribute, as casting closes in on it. It's expensive, wasteful of resources and energy, and, with the advent of other processes, becoming more and more replaceable.

Not to put too fine a point on it, but the K-frame S&W revolvers are forged. They have since been replaced with the L-frame revolver, as durability was lacking. The Ruger Security-Six has never had these durability issues, is the same size as a K-frame, but is cast. The GP100 wasn't a durability replacement, but a move to simplify the inventory, being based on the Redhawk system.

In that case, the "ultimate strength" of the forging obviously mattered little in the end. Oh, and the cast Rugers were taken into service with the military.
 
#57 · (Edited)
JR said:
I was talking about generalizations. There are any number of automotive "forgings" that are machined billets. I believe that it was also brought out that one of the earlier manufacturers "forged" receivers were actually machined from bar stock. How does one produce bar stock? By the way, a couple of the smaller AR companies are supposedly maching lower receivers out of bar-stock aluminum.
No argument on most of your points but lets be realistic. Machining a billet of steel (possibly a forging but most probably an extrusion) into a receiver is more cost prohibitve than machining a shape specific forging. So if there is quantity involved, you better start with a forging.

Aluminum is a softer material and exposes the milling machines and blades, planes, bits, and routers to much less wear and tear. In this instance it may be a wash but my guess is some are machining AR15's from billet soley for the "novelty" of it, to offer something "different". I don't see any advantage whatsoever. In fact, I personally would take the forged receiver before the billet receiver. I don't really care for the "space age" machining look of the billet AR15 receivers.


JR said:
Your comment about other means of producing firearms already shows your bias. Investment casting is another viable method.
I'm speaking of military issue type weapons, not "sporting" weapons. It is not a bias on my part, there just doesn't appear to be any cast military receivers, and no one has come up with any examples.

JR said:
If castings are a thing of the past for firearms, why are so many small parts, even in military weapons, cast? Why would you dismiss Ruger's weapons? They are the largest manufacturer of weapons in the United States. Several thousands of their KP95 pistols have already been accepted by the Automotive Tank Command, and are in-country in Iraq. Ruger's rifles and pistols are the benchmark in durability in commercial weapons. I'd say that the majority of America cares, even if you don't. Otherwise, they wouldn't sell so much, nor enjoy the reputation for durability that they have.
If some military small parts are made from casting they are most likely low stress items. I don't see any receivers made from castings.

Hey, Ruger makes a great firearm for certain cirucmstances and relatively speaking are inexpensive compared to some other manufacturers weapons. Most are considered "sporting" and that is Ruger's stance. Remember old Bill Ruger and his help to Clinton with the so called Assault Weapons Ban? He didn't give a damn about anyone as long as his business wasn't affected. He didn't care about yours, mine, or anyone elses Second Amendment rights as long as he could continue to peddle his wares. That is where my bias to Ruger comes from.

Ruger got the contract primarily because they were cheap and maybe there was a little return favor in there from the Clintonistas.

I would take a nice Glock over a Ruger KP95 which is a boat anchor in my opinion.

JR said:
The military still uses any number of castings for major, and critical parts of systems. Armor plate is cast, ceramics are cast. What process does injection molding most resemble, casting or forging? What is it an outgrowth of?
Armor plate is cast? I think you will find that much of the steel used in armor is rolled plate, kind of a forging. The plasiticized steel is rolled by heavy presses into shape. It is not cast in a mold like we have been discussing unless perhaps it is some specialty item and a shape specific type piece. I will give you that.

Ceramics is a whole nother issue and doesn't belong in this discussion. Injection molding is another issue also. MIM parts in most circles seemed to be frowned upon in a similar fashion as is casting. Perhaps it is traditionalism or if given a choice, people would rather have forged or milled barstock. I personally don't have a problem depending on their useage and correct heat treatement which ultimately may be more important to any part than method of manufacture. I can say though I don't think you will see MIM receivers in the near future.

JR said:
Casting is used in any number of other weapons, from frames and slides, to shrouds and sights. In all too many cases, forging is what's dying away.
Please name some military weapons using cast frames and/or slides. As far as weapons sytems are concerned, the only reason forging is dying is because of steel stampings and plastics.

JR said:
As for the reasoning that led to the M14 being forged, I don't believe that it was an anti-cast bent at all. The men in charge of the rifle were simply not worried about changing materials. After all, "we know that this will work", is a simple reason given by many, instead of thinking. What's the reason some people buy a Ford? "My dad had one" is something often heard, in lieu of true research. Unless you know someone from the team, you're guessing as much as to the sequence of events as anyone else is.
They used forgings because they work.

JR said:
Your discussion of delays does more to bear out what I said than it does to disprove it.
?

JR said:
Just for the sake of injecting logic into the discussion. The M1A cast receiver, by Sa, Armscorp, et al, was to allow them to be built economically. It wasn't a military venture. After over 20 years of service, I'd be guessing that the receivers have proven themselves as far as reliability and durability go. No, the government didn't use casting, but the success of the cast receivers, some of which are now in government service, is a telling point.
FLAG!! What cast receiver is in government service? What is your source for this information? I think everyone on this site would like to hear this.


JR said:
Armasteel was not brought on line to have anything NOW. It wasn't developed until 1943. The use of Armasteel was only allowed in the case of existing contracts having beem filled, and new ones issued. The 1918A2 was a time intensive process, much like the Thompson, and limited facilities were available for their production. Accordingly, the ability to speed production by a factor of six was deemed efficient. Garands, and Carbines were another matter. There had been no research done as to what mods would be needed to use Armasteel. This would have had to been done prior to the change-over, as well as the casting facilities produced and brought on line. Current casting production was already being utilized in the production of armor, artillery, and other critical efforts. If you really think that the military will change from the tried-and-true to a new technology in the middle of a maximum effort, you're delusional.
You made the argument for the ArmaSteel in the 1918A2 receiver. I made the statement it passed muster I believe primarily because of the mass of the receiver. As I stated, millions of other weapons were made and none had cast receievers. In fact, back in the day almost all parts were forged or machined from barstock. I wasn't until later in WWII that stampings came on line. Didn't see much in the way of casting though.

JR said:
This has zero to do with the strength of a forging. That is the ONE thing in favor of an antiquated process. Even at that, it's a dying attribute, as casting closes in on it. It's expensive, wasteful of resources and energy, and, with the advent of other processes, becoming more and more replaceable.
Perhaps you could expound on this for us. Do you have any experience in a foundry or forge? Do you have any formal training in metalurgy, physics, and/or chemistry? Any experience with alloys? Have you ever examined cost analysis on cast versus forged anything? Most importantly, have you ever participated in testing or read any documents comparing one type to the other? Superiority or inferiority? The resultant end product?

I have limited experience but by extrapolation can see that casting of high stress receivers for weapons platforms appears to be nonexistent.

JR said:
Not to put too fine a point on it, but the K-frame S&W revolvers are forged. They have since been replaced with the L-frame revolver, as durability was lacking. The Ruger Security-Six has never had these durability issues, is the same size as a K-frame, but is cast. The GP100 wasn't a durability replacement, but a move to simplify the inventory, being based on the Redhawk system.

In that case, the "ultimate strength" of the forging obviously mattered little in the end. Oh, and the cast Rugers were taken into service with the military.

The K frame was designed in the early part of the 20th century. The only problems with the K arose when magum loads started being used. They weren't even in existence when the pistol was orignially designed! Hardly a valid comparison between a modern Ruger that was designed to handle magnum loads from the outset.

The main reason Smith came out with the L frame (which is larger than the K by the way) is to have a rounded butt for the large frame pistols.

Through all this discussion JR I have yet to have you give us an example of a vialble weapon fielded by any military made with a cast receiver. I have posed this question several times and the only thing I can ascertain at this point is the reason no attempt has been made to answer the question is because no one can come up with an example. All I am getting is smoke and mirrors.
 
#62 ·
You know either way you look at it receivers like the M14 whether forged or cast are more than likely a thing of the past.

The commercial military style firearms business follows demand with cost in mind and demand falls very much in line with whatever the military is using.
The military of today is not looking for receivers like the M14 anymore for new weapons at all because whether cast or forged it's old technology.

The only newer steel receiver weapons are probably only gonna be the squad automatics weapons and larger machineguns like the M2 and these are pretty much stamped steel receivers.

Two of the most likely new small arms to move into larger adoption because one section of the military starts using them I think would be the new FN Scar's and Singpore's Ultimax 100 mod's.
In alot of ways I think the old outlook of what's good for the goose is good for the gander still stands and even if just the Special Forces adopt the Scar's for now and the USMC adopt the Ultimax's, there's a very good chance the others will fall in line in time.

The Ultimax from what I can get out of it is a stamped steel receiver and the Scar's are an extruded aluminum upper with a polymer lower.
How do you think they make that polymer lower too?

The smaller parts also with todays modern investment casting would be more likely cast than being individually forged like the old days and as more advancement comes in new weapons, they may not have as much steel at all anymore.

Whether you like and prefer a forged M14 or cast M14 receiver either way, I think you should just have a Coke and smile and enjoy the old dog because weapons like it are from an era of when they built and did things differently and that era's over.GI7
 
#63 ·
Over?

You'd never prove it by me. The military may not want or need another steel n wood weapon system, but the civilian market is stronger than ever. It's gotten to the point that enough prospective M14 owners want the higher quality of rifles made with forged receivers that companies like LRB Arms are going to be around for a long time. It's reflected in the number of companies now producing high quality replacement parts and more are coming on line all the time.
 
#64 ·
Ted Brown said:
You'd never prove it by me. The military may not want or need another steel n wood weapon system, but the civilian market is stronger than ever. It's gotten to the point that enough prospective M14 owners want the higher quality of rifles made with forged receivers that companies like LRB Arms are going to be around for a long time. It's reflected in the number of companies now producing high quality replacement parts and more are coming on line all the time.
That's not quite what I meant Ted. Not that nobody's gonna want commercial M14's anymore and the market for them is gonna completely dry up. More that receivers like the M14 in the military and the design of the weapon around them is pretty much over.
As for the M14 in general, it's a classic weapon and still one of the best battle rifles today. I think we as the civilian market will always appreciate classics like it besides, but there are many military style firearms enthusiast that will always closely follow the hot new weapons out and want to have what the military has. Isn't that's one of the reasons we're been seeing a building in M14 demand today?
Once the military stops using M14's like they are now and something else takes it's place as it inevitably will, some if not alot of the demand we're seeing now will probably go with it.
Regardless of that, I hope the M14 atleast in the civilian market and companies like LRB as example that make them, are arounding making them for a long time so our generations to come can still experience what a classic steel warrior is like for themselves in all the choices of polymer and light weight weapons of the future.DI5
 
#65 ·
Jose, a list of current cast-frame weapons in service with
the military.
1) New Browning High Power.
2) Manhurin MR-73
3) Ruger P95

There are more, but these will do. Bill Ruger is dead, get over it. Your bias, which you admit, is against the deceased designer of the pistols, and has nothing to do with their abilities. As for the cost, Beretta has supplied tens of thousands of pistols because they were "cheap".

The full-size Glock is larger than a P95. That would then, in your parlance, make the Glock what? A break-water? Oh, see any Glocks in service in the US military? Even the Coast Guard got rid of theirs. Seen Glock get past the evaluation side of any of the latest tests? Nope, all failed early. Glock perfection is an advertisement. Any weapon can, and will wear, or fail. The winners have been Sig, who has used cast slides, and HK.

Armor over 4" or so is cast. Any complex shapes are also cast. The Merkva, an Israeli MBT advertises the use of cast armor on the web-site.

As for the Fulton Armory statement, flag my patooty, the article in the past couple of months SAR states it clearly.
b1Richard brought up the ArmaSteel, not me. You remember, you didn't believe him, either.

For your credentials question, yes, I do, and I have. So, that would make my opinion less believable than yours? You freely admit that you are operating by guess, and by golly.
Extrapolation, from limited experience, usually leads to incorrect assumptions. Adding into the mix political bias, and shifting limits, ends up as just wrong.

The K-frame S&W was an historical pistol. Yet, after WWII, S&W modernized it. They did so with the .357 Mag in existence. In the 1960's they added the chambering to the pistol without any warnings as to longevity, but with much fanfare. It was fully warrantied for use with any standard pressure load that it was chambered for.

Speaking of flags, the N-frame S&W had been available for years with a round-butt. Just for the sake of clarification, the N-frame S&W is listed as the large frame, and always has been. The L-frame was developed to field a durable revolver in .357 for the Police and self-defense owner who wanted a revolver. How you can say that the Security-Six was somehow developed for the .357 (it was first available chambered for that, or the .38 Special) shows that bias, again. S&W wouldn't have warrantied the K-frame if they didn't think that it would last.

Your part in this discussion has gone from cast vs. forged in the M14 receiver, to military only, which none of the M1A rifles, with a couple of noted exceptions, was ever built for. Now, just to limit the field more, we have "I consider these sporting guns", and "they're chosen because they were cheap". Then we have the "viable weapon fielded by by any military with a cast receiver". Hmmmmmm........that was first answered, even to your satisfaction, and roving limits, by the 1918A2. Why are you still asking the same question?

Smoke and mirrors? Nope, how about blinders, on your part. Of course, if you ignore the 1918A2, the several thousand P95 pistols, the BHP, the MR-73, and the Fulton M14, there aren't many left that you couldn't also ignore.

A little more research, sticking to the thread, and a little less bias, would make this a much more pleasant thread.GI2
 
#67 ·
b1richards said:
Jose, Your turn.....
LOL!!!!!!!!! I raced back to the office so I wouldn't miss out! This is better than General Hospital!DI2

Ammo....
The slides on P7/P7M8 H&Ks
Kimbers, down to the Barrels
I believe CZ 75, 85,etc
H&K SL6,SL8,630, 770 recievers and bbl extensions

All this aside, I hate to admit it but if I was told I could only have one rifle, and ZERO replacement parts to rely on, I'd have to choose the G3/91 H&K....Stamped and welded. 5.56 would be the same....G33/93. Second choice would be an FN/JC Higgins (Yes, Sears and Robuck) Mauser with the old style saftey in 30-06 or .270.
 
#69 ·
The 9th Engineer said:
I like M14 type rifles!!!DI2
Anyone else??
I'm quite fond of them actually.GI7
I guess that's why I'm looking at buying another after I get a new M1 Carbine.

Gonna have probably pass on a Scout for now though. Strangely enough my chromelined fullsize with Smith's hooded GFLS and DC Vortex seems to be short enough for me at 6'4".

Gonna have to pick up a nice NM next instead.
The chromelined in a modded usgi fiberglass, and a NM in a JAE-100 with a competition stock on the side will fill all my needs I think.

One for long and precise and one for mid and fast. DI5 Yep, that's pretty fulfilling.
 
#70 ·
The 9th Engineer said:
I like M14 type rifles!!!DI2
Anyone else??
Yepper! I have a little LRB Tanker that is a sweetheart! I've had that M1A/M14 needle in my arm for 30 years, and there aint no cure! I'll take a cast SAI anyday too!!! I'd like to build a Tanker in 7mm-08, but that's another thread. Wouldn't care if it was cast or forged.DI5
 
#72 ·
Cast vs Forged vs Bar Stock

This is a subject that I have a modicom of experience about. I manage a machining company that is currently furnishing kits for the Marine Corps up-armored HUMVEEs. My experience spans almost 30 years in the metal working industry.

The Gov. spec. called for the M-14 recievers to be made from AISI 8620 steel. This steel is not a "direct hardening" steel, it's chemical compisition was formulated for "case hardening. This is a process where additional carbon (8620 has only .20 % carbon and will not harden without adding carbon) is added during the heat treat process. This process is sometimes called "carburizing". It then has a hard surface approx. 0.015 inch deep and a tough ductile core. This will then handle heavy shock loads but have good wear resistance due to the surface hardness.

First a bit of background info for those not familiar with these three processes.

Usually steel starts out as a cast "pig" from the kettle and is then run (while still red hot) through a series of pressure rollers that form the final shape. It is then allowed to cool. This is called "hot rolled" steel. "Cold rolled" steel is made by continuing the rolling process after the steel has cooled to near ambient. Cold rolling is used primarily for industrial machine parts and shafts. It has a lot of residual stresses built up in it and can go crazy with distortion when a lot of metal is removed during machining process. Hot Rolled is usually stable but requires scale removal for nice looking machinery parts.

Forging takes a billet of steel (hot rolled) and is heated to a temperature where the steel becomes "plastic" I'm not sure but probably around 1500 deg. F. The billet is then formed to a net shape that has enough material to be removed by machining. Forging reshapes the grain structure of the steel to conform to the shape of the part. This grain structure gives an inherent strength to the part.

Casting is of course steel melted to a liquid and poured into a net shape mold. Cast steel has a random grain structure as cast and usually requires a another heat process to orient and reshape the grain structure.

Machining from bar stock a highly stressed part is not ideal unless the parts has been designed with a high safety factor. The grain structure is oriented parallel to the longitude of the rolled bar. Machining sharp corners in highly stressed parts made from bar is not recommeded, because a crack can begin in sharp corner (or sharp edge) due to the grain structure.

I suspect that the reason the M-14 and the M-1 Garand recievers were spec'd as forgings was due to the quality of casting back in their day. Forging guaranteed a quality reciever due to the reshaping of it's grain structure. Investment casting and heat treating processes have come a long way since the 1930's & 1940's.

My opinion is that a forged reciever is best, cast second, and bar stock last.
 
#73 ·
The 8620 that M14's are made of is a wonderful steel. This week I recieved 145 tooth gear with 16 tooth pinion that I made in 1994. They have run night and day 6 days a week ever since I made them. the pinion I made of 8620 which I had carburized with .015 case and the gear which was made of a 4150 forging and was left as is. The pinion has almost no wear at all and the gear is worn quite a bit. The surface of the pinion is like glass while the core is ductile and very strong. It would be interesting to know how many times each tooth on the pinion engaged a tooth on the gear. I would imagine a forged or a cast M14 would last forever if kept clean and well greased.
 
#74 ·
Yes, 8620 is a great steel, note the chromium content, there is the reason it has such great wear characteristics. And the molydenum helps give lubricity to that hard surface.


Carbon 0.18 - 0.23
Chromium 0.4 - 0.6
Manganese 0.7 - 0.9
Molybdenum 0.15 - 0.25
Nickel 0.4 - 0.7
Phosphorus 0.035 max
Silicon 0.15 - 0.35
Sulphur 0.04 max

AISI 8620 is a hardenable chromium, molybdenum, nickel low alloy steel often used for carburizing to develop a case-hardened part. This case-hardening will result in good wear characteristics. (from a steel data handbook of mine)
 
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