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AR-15 barrel material

7.62x39Lover7.62x39Lover Member Posts: 3,937 ✭✭✭
edited May 2012 in Ask the Experts
Hi guys. What do you guys figure is the best material for an AR-15 barrel to be made of? Is 410 steel OK? I came across a 20", 1:7, hammer forged heavy barrel that looks good to me ($299.00 410 Steel).
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Comments

  • Bill JordanBill Jordan Member Posts: 1,402 ✭✭✭✭✭
    edited November -1
    It googles as an OK choice,; if I remember ( it's been 15 yrs), FNMI uses 8650 for the M16.
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  • nononsensenononsense Member Posts: 10,931 ✭✭✭✭
    edited November -1
    7.62x39Lover,

    The call out 410 for a stainless steel is similar to 416R except it has less sulfur. Sulfur is added to steel for increased machineability but the drawback can be a potential for microscopic weakness at extremely cold temperatures (-40F). This was discovered when Sako had barrel failures on skinny contours a few years back. Krieger tried to make a big point of switching to 410 for the smaller sporter contours directly after the failures hit the media but it basically was ignored.

    While you're at it, 416R is a proprietary formula from Crucible Steel and is not a generic alloy so all of those barrel makers and steel producers who claim to make/use 416R Crucible are either in violation of a protected formula or they are lying. Krieger has the rights for making the statement since they entered into the agreement with Crucible.

    Best.

    ADDED:

    The 'R' is only a part of the whole. The complete term is 416R Crucible which makes the formula proprietary. Many steel makers use specific terms for steels formulated by them even though they may share similarities with steels from other manufacturers. 'Stressproof' is one that comes to mind readily as an example.

    Best.
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  • dcs shootersdcs shooters Member Posts: 10,969
    edited November -1
    Nononsence has it right. Most barrels are 416R. I's because 410 is harder and wears tooling faster. We did a few thousand SPR barrels and the suppler said they were 416R SS.
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  • kylewkylew Member Posts: 95 ✭✭
    edited November -1
    When nonon says that 416R is proprietary he may be correct The "R" I am unfamiliar with. 416 SS is an ASTM spec and it does come in at least two and most likely more sub grades. I know it comes in 416 and 416HT (heat treat). So I am unaware of the spec for the "R". 416HT is very machinable is tougher than ASTM4140. 416 is slightly magnetic and will rust. 300 series is not magnetic but is much softer and has better corrosion resistance. Maybe one of them can tell su what the R stand for? K
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  • dcs shootersdcs shooters Member Posts: 10,969
    edited November -1
    416R means it is 416 stainless steel for Rifle barrels.

    The R stands for RIFLE [:0]
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  • v35v35 Member Posts: 12,710 ✭✭✭
    edited November -1
    R should mean resulphurized.
    Sulphur aids machinability but otherwise isn't a great element in steel.
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  • kylewkylew Member Posts: 95 ✭✭
    edited November -1
    I learned something new today. Thanks. BTW nonon Thanks for the photos, my brother is MIA 44 years. May 12,68 (Mothers day) Kaum Duc VN.
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  • 7.62x39Lover7.62x39Lover Member Posts: 3,937 ✭✭✭
    edited November -1
    Thanks again for all the great info. I will snatch up that barrel ASAP.
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