357smallbore
Member
Which application do you believe is best for a handgun
Forged, Cast & MIM. What's better and why
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Jim Watson
Member
Don’t forget billet. Cabot says billet is best.
Depends on the part. Obviously some parts of a handgun can be made from aluminum, pot metal, or plastic and still provide good service life and proper function.
I don't think firing pins or barrels should be made from cast metal or MIM, but a magazine release, trigger, trigger bar, decocking/safety lever, etc. could be made with MIM or by being cast and as long as the QC was good and the design was proper, they shouldn't break.
I don't think firing pins or barrels should be made from cast metal or MIM, but a magazine release, trigger, trigger bar, decocking/safety lever, etc. could be made with MIM or by being cast and as long as the QC was good and the design was proper, they shouldn't break.
WestKentucky
Member
If going for strength then forged is high up the list. Milled from bar stock is best (billet by common nomenclature).
The big things are grain structure, porosity, and stress. Bar stock or billet material is made in such manner to have the most uniformly good quality of whatever metal it is. Very very little if any porosity or internal stress. Generally the most best and most uniform grain structure, unless heat treated or quenched when formed but even still great material.
Forged… hot forge… bar stock is heated to near melting point, and formed by force whether that be squeezing in a press, hit by hammer, upset into a mold, etc. Cold forge… primarily things like barrels. It’s worked by striking and compressing in a controlled manner. Hot forging leaves a little stress. Cold forging leaves more stress but cold forging is generally not doing major shaping changes. Still very little if any porosity, grain structure relatively unchanged.
Cast… molten material poured or injected into a mold and allowed to cool. Under perfect scenario extra material is used to push air out of the mold and the mold is made in such manner to help air escape. There is porosity in cast metals. Period. Different metals get porosity at varying degrees but there will be tiny air bubbles in the metal. Possibly inclusions of other materials from the mold or process. The casting will then have to cool off, and hopefully will cool uniformly and slowly or it can impart stresses from contracting at different rates. Complex shapes like pistol frames or AR lowers can be cooled slowly to avoid cracking but if quenched there’s a good chance that they are cracking. Grain structure depends upon conditions of the casting.
Stamped takes flat stock, usually some form of bar stock that has been mechanically flattened to a given thickness. Stamping dies both form and cut material under high pressure. This can leave a lot of stress in the parts, but since it’s essentially just re-formed bar stock it’s pretty good. Stamping has limitations though and for guns the shapes are generally too intricate or require thickness and shapes that just don’t make sense for stamping unless it will be multiple parts welded together in which case you often have slightly different material in welding material, porosity in the weld, stresses in the metal as the metals heat and cool quickly. This can be done quite well, but the guns either look and feel cheap, or they need a good bit of work after this process to look like much. Think liberator pistol, ww2 grease gun.
So depending upon what the part is or what attributes it needs… any of the types of material forming can work. It’s just a factor of picking the process that leaves the best qualities to meet criteria. Strong and pretty- probably billet that’s machined. Strong and looks don’t matter, stamped. Built quick to win a war, stamped and welded is a proven winner.
The big things are grain structure, porosity, and stress. Bar stock or billet material is made in such manner to have the most uniformly good quality of whatever metal it is. Very very little if any porosity or internal stress. Generally the most best and most uniform grain structure, unless heat treated or quenched when formed but even still great material.
Forged… hot forge… bar stock is heated to near melting point, and formed by force whether that be squeezing in a press, hit by hammer, upset into a mold, etc. Cold forge… primarily things like barrels. It’s worked by striking and compressing in a controlled manner. Hot forging leaves a little stress. Cold forging leaves more stress but cold forging is generally not doing major shaping changes. Still very little if any porosity, grain structure relatively unchanged.
Cast… molten material poured or injected into a mold and allowed to cool. Under perfect scenario extra material is used to push air out of the mold and the mold is made in such manner to help air escape. There is porosity in cast metals. Period. Different metals get porosity at varying degrees but there will be tiny air bubbles in the metal. Possibly inclusions of other materials from the mold or process. The casting will then have to cool off, and hopefully will cool uniformly and slowly or it can impart stresses from contracting at different rates. Complex shapes like pistol frames or AR lowers can be cooled slowly to avoid cracking but if quenched there’s a good chance that they are cracking. Grain structure depends upon conditions of the casting.
Stamped takes flat stock, usually some form of bar stock that has been mechanically flattened to a given thickness. Stamping dies both form and cut material under high pressure. This can leave a lot of stress in the parts, but since it’s essentially just re-formed bar stock it’s pretty good. Stamping has limitations though and for guns the shapes are generally too intricate or require thickness and shapes that just don’t make sense for stamping unless it will be multiple parts welded together in which case you often have slightly different material in welding material, porosity in the weld, stresses in the metal as the metals heat and cool quickly. This can be done quite well, but the guns either look and feel cheap, or they need a good bit of work after this process to look like much. Think liberator pistol, ww2 grease gun.
So depending upon what the part is or what attributes it needs… any of the types of material forming can work. It’s just a factor of picking the process that leaves the best qualities to meet criteria. Strong and pretty- probably billet that’s machined. Strong and looks don’t matter, stamped. Built quick to win a war, stamped and welded is a proven winner.
Right.
If the appropriate process is not selected correctly and the manufacture does not follow the appropriate processes, your get junk.
I'd think that most reputable gun manufacturers would make parts reliable for the application they are designed for.
I've not had issues with MIM parts in S&W revolvers.
Bubba's Saturn Day Night Special Gun emporium is a different matter.
In the 1980's, I worked for a Nickel and Cobalt refining company. We refined Nickel and Cobalt into powders and then sintered them in to briquets for adding to steel for alloying. The sintered briquets were very tough. Not that these process wold be used for individual parts but the process showed what could be had wkth the sintering process. Make a mould of an appropriate part, sinter it, and you have a tough part for an appropriately deigned part.
Granted, the MIM process is a bit more refined than the sintering briquets we made for alloying steel, but it shows what could be done with the basic process.
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Really depends on the application. Forged receivers for HP rifle applications is best. Mim has come a long ways from it's earlier days and is used in all production firearms to some extent. The bad rap for mim still follows it from it's earlier days and the internet. Bar stock hand fitted parts in high dollar custom pieces of course and you pay for it...
earlthegoat2
Member
If efficiency of time and materials is thrown out the window and you want a no compromises type of build then forged and billet is likely very close to the best.
jar
Contributing Member
Well made is better than poorly made.
It depends on the part and what is expected.
It depends on the part and what is expected.
bangswitch
Member
I like forged parts best, like the older S&W's use for hammer and trigger, instead of MIM. As for cast vs forged both have to be finished by some means and a cast part can be just as strong as a forged part. MIM is my least desired.
Jim Watson
Member
Looking at some of Driftwood Johnson's S&W sideplate off pictures, I note that MIM parts have been redesigned with the minimum of holes and slots, a lot of parts interlock rather than being pinned together. Seems like a mold with internal shapes to form holes would be a lot more complicated and expensive.
I was surprised to read a post that they are making MIM barrels for the Chief's Special, even though it is a small part for a low pressure round.
I was surprised to read a post that they are making MIM barrels for the Chief's Special, even though it is a small part for a low pressure round.
Hey, I live just across the Tennessee River from Colbert County and agree they could use some refinement.
doubleh
Member
It depends. Ruger has used MIM for so long I have forgotten when they started doing it. How many Rugers have you ever heard of breaking apart? For a long time forging and machined from billet was the only option. Other methods have been developed to reduce overall cost. As long as the process produces materials adequate for their use I see little difference to the end user except cost. It is all about stress to the part. If cast or MIM produce a part strong enough to hold up to it's job it lowers manufacturing costs. The naked eye will see no difference if the finish is done well.
Dave DeLaurant
Member
The specific alloys used should be a variable of equal or in some instances greater importance.
For example, Mauser 98 receivers have been manufactured by approximately the same processes from both relatively low-carbon steels and high strength alloys.
For example, Mauser 98 receivers have been manufactured by approximately the same processes from both relatively low-carbon steels and high strength alloys.
Please, can someone explain any differences between MIM and cast?
I understand that MIM likely means casting under pressure whereas casting could be both; under pressure or using gravity (is centrifugal casting considered pressure/MIM?) but, AFAIK, the pressure casting process has been used for years and not been called MIM.
Is it just a fancy way of saying pressure casting?
Thanks in advance
I understand that MIM likely means casting under pressure whereas casting could be both; under pressure or using gravity (is centrifugal casting considered pressure/MIM?) but, AFAIK, the pressure casting process has been used for years and not been called MIM.
Is it just a fancy way of saying pressure casting?
Thanks in advance
buck460XVR
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- 10,083
IMHO, what material is used, is not as important as the quality of the material being used or the quality of the assembly of the parts. Quality stamped parts will perform better than poorly machined parts.
mcb
Member
I am a mechanical engineer by education and profession and have used all three processes in various project I have worked on. There is a fair amount of overlap to all three process but they each have their strengths and weaknesses. At their core they are all cheap and fast ways to get near net shape of a part reducing the amount of machining required to achieve the final shape.
MIM can do smaller features more accurately than the other two process but can't be used to make large parts. (Not much larger or thicker than your out spread hand in most cases.). As an example of the details that can be forged S&W has made 380 body guard barrels from MIM with no post machining, including having MIM'ed the riflings.
Yes MIM had is problems back when the technology first came into the firearms industry in the 80's and early 90's. Between being new a technology (the firearms industry played a big role in the technology's maturity) in and of itself and being a new technology to that generation of firearms engineers lead to some issues both in the technology and the way it was being used. At this point in time 30+ years later the technology is mature and a new generation of engineers "grew up" using it.
A properly design part that is MIM will be more dimensionally consistent and require less post machining than any other near-net-shape process currently available. It is cost effective and results in better parts when used correctly. Proper heat treat and if the application demands it the H.I.P. processing results in material properties that are indistinguishable from billet of the parent metal.
Forging has the advantage of working hardening the parts as part of the forging process that can have beneficial properties as it strengthen the material compared to a normalized or annealed billet of the same material. That said with most steel alloys to maximize the metal's properties you still need to heat treat the parts post forging but frequently the post forged metal properties are good enough for the application and you can skip the heat treatment. Forging is fast once the forging dies have been created especially if the part requires minimal post forging machining and no heat treatment.
Casting can capture details finer than forgings and do shapes that a forging process cannot capture. Casting cannot replicate the fine details MIM can. Casting can do larger parts better and more cost effectively than the other two. ie You can cast a Tank hull for a fraction of the cost of forging that shape and do it in one part not several.
The alloy used plays a huge role in the final material properties. This cannot be stressed enough. Using the right material with the right heat treatment for the part is as critical as the part being the right shape.
Obviously the precision the parts are made to, plays a huge role too.
So MIM's, vs Forged, vs Cast all comes down to the application. There is no general, best process though in specific cases we could probably pick a winner or a looser. Even within the creation of a handgun all three application can be used successfully depending on the specific part.
-rambling
MIM can do smaller features more accurately than the other two process but can't be used to make large parts. (Not much larger or thicker than your out spread hand in most cases.). As an example of the details that can be forged S&W has made 380 body guard barrels from MIM with no post machining, including having MIM'ed the riflings.
Yes MIM had is problems back when the technology first came into the firearms industry in the 80's and early 90's. Between being new a technology (the firearms industry played a big role in the technology's maturity) in and of itself and being a new technology to that generation of firearms engineers lead to some issues both in the technology and the way it was being used. At this point in time 30+ years later the technology is mature and a new generation of engineers "grew up" using it.
A properly design part that is MIM will be more dimensionally consistent and require less post machining than any other near-net-shape process currently available. It is cost effective and results in better parts when used correctly. Proper heat treat and if the application demands it the H.I.P. processing results in material properties that are indistinguishable from billet of the parent metal.
Forging has the advantage of working hardening the parts as part of the forging process that can have beneficial properties as it strengthen the material compared to a normalized or annealed billet of the same material. That said with most steel alloys to maximize the metal's properties you still need to heat treat the parts post forging but frequently the post forged metal properties are good enough for the application and you can skip the heat treatment. Forging is fast once the forging dies have been created especially if the part requires minimal post forging machining and no heat treatment.
Casting can capture details finer than forgings and do shapes that a forging process cannot capture. Casting cannot replicate the fine details MIM can. Casting can do larger parts better and more cost effectively than the other two. ie You can cast a Tank hull for a fraction of the cost of forging that shape and do it in one part not several.
The alloy used plays a huge role in the final material properties. This cannot be stressed enough. Using the right material with the right heat treatment for the part is as critical as the part being the right shape.
Obviously the precision the parts are made to, plays a huge role too.
So MIM's, vs Forged, vs Cast all comes down to the application. There is no general, best process though in specific cases we could probably pick a winner or a looser. Even within the creation of a handgun all three application can be used successfully depending on the specific part.
-rambling
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sgt127
Member
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I had the slide stop break on my older Kahr K9
Pretty sure it was just cast. Really grainy.
The seams were pronounced.
The replacement looks like MIM. With the number cast into it. It’s just a generally smoother finish.
So, apparently Kahr decided MIM was better for that part than casting.
As an aside, they have another slide stop that’s two piece. They are not interchangeable.
Pretty sure it was just cast. Really grainy.
The seams were pronounced.
The replacement looks like MIM. With the number cast into it. It’s just a generally smoother finish.
So, apparently Kahr decided MIM was better for that part than casting.
As an aside, they have another slide stop that’s two piece. They are not interchangeable.
You are probably right, but I meant yo say cobalt, the metal.
Jim Watson
Member
Oh, I know what you meant, just that my location made it a convenient joke. The autocorrect author was probably thinking of the TV jokester-Liberal shill.
Creaky_Old_Cop
member
Forged is always going to be "better", ask any machinist. The real question is "How much better do YOU need it to be"? I shot a Kimber one match season when I was still competing in Single Stack almost exclusively, and put a documented 53,000 rounds through it in that year. None of the boogeyman MIM parts failed. Conversely, I built a Stacks gun on a Springfield, and replaced the "looser than I like" bushing with a Wilson Combat bushing and it blew out the front end and went tinking down the range at a USPSA match after less than 500 rounds.
Jim Watson
Member
Right, my High MIM Springfield IDPA ESP is holding up well with original - but honed - hammer, sear, safety, and disconnector.
I replaced the slide stop but that was on me, it was prone to premature engagement by bullet bump and when I filed the lug I took off just a smidgen too much and it would then not always engage when empty. So I put in a new one, no doubt 10-8 uses superior materials.
I replaced the slide stop but that was on me, it was prone to premature engagement by bullet bump and when I filed the lug I took off just a smidgen too much and it would then not always engage when empty. So I put in a new one, no doubt 10-8 uses superior materials.
EMC45
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I like the "subtle" grip over layment.
