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Thread: 4140 CMV...4150 CMV...does it even matter?

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    4140 CMV...4150 CMV...does it even matter?

    Since Daniel Defense has stopped using 4150 CMV and gone to 4140 CMV, I looked up the steels, and I wonder...does it even matter?


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    Not to me

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    Quote Originally Posted by WS6 View Post
    Since Daniel Defense has stopped using 4150 CMV and gone to 4140 CMV, I looked up the steels, and I wonder...does it even matter?
    Source? Their site still says CMV = 4150. There's no such thing as 4140 CMV, as the "V", Vanadium is the added element to achieve the additional carbon to reach 4150.
    Last edited by ASH556; 02-10-14 at 14:47.
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    Both are 41XX series which denotes the alloying elements such as chromium, vanadiuim etc. The 40 and 50 refer to the carbon content in tenths of a %, respectively. IE: 4140 has a nominal carbon content of 0.4%, 4150 has a nominal carbon content of 0.5%.
    I'm assuming you knew that; I guess what I'm saying is that adding vandaium doesn't add to the carbon content. Actual carbon is what's added. I don't know off the top of my head what the percentages and alloying elements are for either steel. I also think there are other specs for 4140 and 4150 than just AISI - which is what I'm thinking of.

    Quote Originally Posted by ASH556 View Post
    Source? Their site still says CMV = 4150. There's no such thing as 4140 CMV, as the "V", Vanadium is the added element to achieve the additional carbon to reach 4150.
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    Quote Originally Posted by Eric D. View Post
    Both are 41XX series which denotes the alloying elements such as chromium, vanadiuim etc. The 40 and 50 refer to the carbon content in tenths of a %, respectively. IE: 4140 has a nominal carbon content of 0.4%, 4150 has a nominal carbon content of 0.5%.
    I'm assuming you knew that; I guess what I'm saying is that adding vandaium doesn't add to the carbon content. Actual carbon is what's added. I don't know off the top of my head what the percentages and alloying elements are for either steel. I also think there are other specs for 4140 and 4150 than just AISI - which is what I'm thinking of.

    Apparently I mis-understood this part then:

    Quote Originally Posted by BravoCompanyUSA View Post
    11595 Barrel Steel ?
    4150 Barrel Steel ?
    Chrome Moly Vanadium ?
    4140 Barrel Steel ?


    There has been a lot of discussions about some of the differences and some of the not-so-differences between these descriptions. This post is in an effort to help clarify some issues as it relates to barrel steel.

    4140 grade of steel – The “40” in 4140 is specific to the amount of carbon in the alloy. Generally it is near .40%.

    Likewise the “50” in 4150 steel is an indicator that the barrel steel has a carbon content near .50%

    An 11595 barrel steel (Mil-Spec) gets its additional strengthening properties over the common commercial 4140 by one of two ways;
    more carbon in the steel
    -or -
    more carbon with the addition of Vanadium.

    The specific chemical composition of all Mil-Spec barrel steel is listed below in MIL-B-11595E. This specification outlines the use of barrel steel under 2 inches in diameter for manufacturing barrels for small arms. That can encompass a lot of different small arm weapons.


    When purchasing steel from a mill the certification paperwork and other relevant paperwork usually lists a “Grade” of steel and then adds further details under the heading of “Specifications”. For a Mil-Spec barrel steel; that specification would be listed as MIL-B-11595E. This is to say that not all 4150 steels are considered Mil-Spec. In order for it to be Mil-Spec it would need to be a 4150 grade AND it would have to comply with the specifications listed in 11595.

    Table One (listed above) shows three types of chemical compositions and ranges for Mil-Spec 4150 barrel steel as defined by 11595.
    ORD4150, ORD4150-Resulferized, and Chrome-Moly-Vanadium (CMV) should not be confused with the generic term of a Chrome Moly barrel. My opinion and the opinion of the US Government (as defined by the Mil-Spec) is that one of the three is not better than the others. They are all they same and are all 11595 (Mil-Spec) barrel steel. In some descriptions used by steel companies I have seen the Grade of CMV further listed as 41V45, which is a bit more descriptive, but probably just add confusion in this context.

    While doing some research on a project we are putting together in house, I was told by several reputable folks in the barrel business that Colt uses CMV. I was under the general impression that Colt specifically used ORD4150. Maybe I was programmed to think that way because it is all generally listed under the “Grade” of 4150. So in order to have accurate data to work with, I submitted a Colt 14.5” M4 SOCOM barrel for destructive testing chemical analysis. I received the results recently and that barrel that was made in November 2000 was determined to specifically be CMV.
    (Results DT and chemical analysis document listed below)


    (As a side note, all weighted percentages were within the Mil-Spec range.) This also matches the results of DT done previously on a FNMI barrel. I acknowledge this evidence is anecdotal when applied to looking at all M16/M4 barrels, but it is interesting non the less.

    So in describing a USGI M16/M4 barrel it is generally done this way on spec sheets:

    Barrel Steel
    Grade: 4150
    Specification: Mil-B-11595E
    And then as part of the certification documents would be the chemical analysis to list CMV.
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    There is such a thing as 4140 CMV. Now, if it's used in the firearms industry or not, I'm not sure, but 4140 CMV is a thing. The only element added to achieve more carbon is carbon; adding vanadium doesn't magically increase the carbon content. Vanadium can be added completely independently of the carbon and vice versa. Not that you would/wouldn't want to do that (the vanadium may be necessary to achieve proper strength with extra carbon; I'm not sure), but there is such a thing as 4140 CMV, at least colloquially.

    The only difference 4140 CMV and 4150 CMV would have in the grand scheme of things (other than a few hundredths of percents of certain elements) would be the carbon: 0.40% and 0.50%.
    Last edited by DreadPirateMoyer; 02-10-14 at 15:37.

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    Yes vanadium and carbon added independently. Sorry, it was your wording that threw me off.

    Quote Originally Posted by ASH556 View Post
    Apparently I mis-understood this part then:
    This is what I was trying to say:

    Quote Originally Posted by DreadPirateMoyer View Post
    The only element added to achieve more carbon is carbon; adding vanadium doesn't magically increase the carbon content.
    Last edited by Eric D.; 02-10-14 at 16:44.
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    you wont be able to tell the difference so I wouldnt worry too much
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    When researching the difference between the steels, I came across a discertation by an SME/industry insider that said 4150 CMV had an edge in heat dissipation. I don't remember where or by who, unfortunately. For myself, I don't think I'll see a difference between 4150 CM & 4150 CMV. 4140 CM may not last as long as 4150 CM or 4150 CMV for a 5.56, but 4140 CM and 4130 CM have proven their durability in FAL 308 barrels.

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    WS6, where did you find this info? Im curious as their site simply lists their barrels as CMV, which, to me meant it complied with the above chart. Not sure what the difference is between 4140cmv and 4150 cmv or where they stand compared to the given spec sheet but I'm of the opinion that most will likely never notice the difference. That said, I'm also of the opinion that there's no reason to "skimp" with the availability of options these days.

    ETA: If you look at the carbon content requirement under mil-B-11595E, the given range appears to be the average of both 4140 and 4150 CMVs. Based on WS6's charts, the only diff if we want to be real nit-picky, is .005% in phosphorous content. I'm no metallurgist but i dont know if that even matters.
    Last edited by Col_Crocs; 02-10-14 at 18:29.

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