.40 S&W

This is a discussion on .40 S&W within the Defensive Ammunition & Ballistics forums, part of the Defensive Carry Discussions category; Anyone know why the .40 S&W has a flat top as opposed to a rounded nose? Some other calibers are like this as well. The ...

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Thread: .40 S&W

  1. #1
    Distinguished Member Array Pro2A's Avatar
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    Question .40 S&W

    Anyone know why the .40 S&W has a flat top as opposed to a rounded nose? Some other calibers are like this as well. The .44 Mag comes to mind as one.

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  3. #2
    VIP Member Array glockman10mm's Avatar
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    You are referring to bullet type, not specific to any one caliber. You can get the flat profile bullet in almost all calibers. It is generaly referred to as trunicated flat nose or swc.

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    Distinguished Member Array Pro2A's Avatar
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    Well I guess my question is why are some like that and others not? It seems like whenever I buy standard 9mm or .45 it's all rounded. The standard .40 round however seems to be flat when I buy it commercially.

    Also what does a flat top do to the ballistics of the round when it hits?

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    VIP Member Array Cuda66's Avatar
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    Quote Originally Posted by Pro2A View Post
    Well I guess my question is why are some like that and others not? It seems like whenever I buy standard 9mm or .45 it's all rounded. The standard .40 round however seems to be flat when I buy it commercially.

    Also what does a flat top do to the ballistics of the round when it hits?

    Like was pointed out above--it's just bullet design.

    I've bought commercial 9mm FMJ's that had more of a flat point than a round nose; I've also bought .45 FMJ with a similar profile...and, I've seen .40 FMJ with a round nose.

    Just different manufacturers is all.

    As to what it does when it hits...if the flat point has a sharp enough shoulder, it will cut a hole at about the same size as the flat point, where a round-nose bullet tends to (especially in flexible stuff) allow whatever it's passing through to stretch around it, making a smaller hole.
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    Distinguished Member Array svgheartland's Avatar
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    Hmmmm. I just looked in my Hornady reloading; Vol 1. All 40 and 10 mm are flat. No exceptions. I know, Hornady isn't the final word in loading. Having owned and shot both, my subconcious realized that they were all flat but I never asked the question. It was all factory ammo. And I haven't reloaded any so I never got to that point. I'll assume it's action design/feeding related but I'll watch as responses come in.
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  7. #6
    Distinguished Member Array Pro2A's Avatar
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    I have the "Cartridges of the World" catalog and the .40 S&W pictured in the book is flat as well. It's good to know I'm not going crazy.

  8. #7
    VIP Member Array zacii's Avatar
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    I noticed the same thing. Whenever I buy .40 fmj, it's always flat nose, don't know why. Maybe it's to help identify it from the 9mm so you don't accidentally load the wrong caliber...
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    VIP Member Array cmdrdredd's Avatar
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    There's two schools of thought that I've read with this, both sound likely.

    1) The flat nose is to give a similar OAL(overall length) as a 9mm round so that the .40sw can be fired from a firearm that is the same size as a 9mm firearm.

    2) The flat nose is used to give the profile similar to a JHP round and thus any firearm that can load and fire a flat nose round can chamber a JHP just the same.
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    Ex Member Array Ram Rod's Avatar
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    Quote Originally Posted by cmdrdredd View Post
    There's two schools of thought that I've read with this, both sound likely.

    1) The flat nose is to give a similar OAL(overall length) as a 9mm round so that the .40sw can be fired from a firearm that is the same size as a 9mm firearm. that really doesn't make sense since firearms of different calibers rely on the chamber measurements for the specific caliber. The OAL should have nothing to do with it.

    2) The flat nose is used to give the profile similar to a JHP round and thus any firearm that can load and fire a flat nose round can chamber a JHP just the same. I actually don't know where this came from, but if you think about it, and read that statement again, it also doesn't make sense.

    Great post actually.....but dispel the myths. Ballistics and design pretty much go hand in hand. Rifling twist, length of barrel, bullet weight, and velocity. All of these things rolled into one affect the stability of the particular bullet once it leaves the muzzle for it's weight as it goes downrange for the velocity it's traveling at ever increasing distances. The bullet design for the weight is generally the best for the velocity expected. Realize that the 40S&W caliber alone approaches the limits of all involved in modern pistols, and hence we see few of the RN FMJ as compared to the TMJ rounds that are more common for range ammo. A flat nosed or truncated cone gives a bit more resistance while in flight and hence balances out the velocity for the shorter range of twist and travel through the barrel. Simple physics for the engineer, and questions for us. JHPs in 40S&W can be designed as most PD ammo in other calibers because of the resistance encountered while going downrange. FMJ or TMJ ammo for the 40S&W is so designed for the accuracy expected out of most pistols in other calibers. The 40S&W is the hi-power for it's caliber while other calibers have room for improvement in their specific calibers. Who wants a bullet that will fragment five feet from the muzzle? The 40S&W is pushing the limits of the caliber from it's inception, therefore it needs more stringent rules to live by.

  11. #10
    VIP Member Array cmdrdredd's Avatar
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    Well, if you think about the idea that the .40 isn't much longer than the 9mm round then you can make the assumption that it will fire from a pistol with the same sized frame. Think the Glock 19 and Glock 23. Same frame all around.

    I think that's where this idea came from. Shoot a .40 from the same sized gun as 9mm, so you don't need a big gun like the bren ten.

    The idea that the flat nose gives a similar profile to a JHP might lead someone to believe that they designed it thus so that guns chambered for .40sw would more reliably chamber JHP. I'm not saying it's right, it's stuff you read on the internet afterall.
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    Distinguished Member Array svgheartland's Avatar
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    Ram Rod....ok first, I bow to you if you are correct and I tend to believe that that's the case. Excellent explanation and, being of the great unwashed, I cannot doubt it. Can I assume, given the history of the 10mm and then the 40, that this also applies to the 10?
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    Ex Member Array Ram Rod's Avatar
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    So how does the range ammo availability for the 45G.A.P. weigh out in the scheme of things? I don't know actually...that's why I'm asking. It's available in the same frame size pistols as the 9mm. Of course we know the 357SIG is available in the 9mm size pistols, but the case and overall cartridge had been re-designed. Designed for the best ballistics. What are the 357SIG folks seeing in the way of range ammo compared to PD ammo?
    I'm not saying it's right, it's stuff you read on the internet afterall.
    I'm not calling anyone out either, and I'd never do that here amongst family for sure. Thing is, misconceptions abound, and we're pretty much lead to misunderstand things without a basic foundation. That's how our government works against us every single day (since they learned how and we showed them the way). My apologies for getting somewhat off topic here.

    Originally Posted by svgheartland View Post
    Ram Rod....ok first, I bow to you if you are correct and I tend to believe that that's the case. Excellent explanation and, being of the great unwashed, I cannot doubt it. Can I assume, given the history of the 10mm and then the 40, that this also applies to the 10?
    Never bow to anyone plain and simple.
    Doubt everything you hear until proven by yourself.
    Never assume anything.
    Be sure of one thing.....the ballistics of any given caliber rely on it's design, and the design relies on ballistics. Just the simple rules of earth and it's properties....physics, and those respected in the past for their contribution toward our understanding of such like Einstein and Newton.
    Without looking at the big picture......there's a reason for everything.

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    Senior Member Array kylebce's Avatar
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    Good points by RamRod.
    Most pistol cartridges have been around a long while. The 9mm, .38 & .45 were all used in WW2. Full metal jacket is the Geneva Convention rule in combat.

    The 10mm was developed in the 1980's to be the ultimate law enforcement caliber. The accepted "best design" by that date was jacketed hollow points. So- the magazine, frame, feed ramp were all designed specifically for HPs. When FMJ was introduced for range use & competition, it had to have the same "shape" or dimensions to fit in the same magazine, frame, feed angle, etc.

    The 10mm proved to be "too much" recoil for some female agents and small handed guys. So they necked it down- giving birth to the .40S&W. It's nose was flat- just like big brothers for the same reason.
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    Senior Member Array ZX9RCAM's Avatar
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    I have a threaded conversion barrel for my Glock 22 so that I can shoot 9mm out of it.....just sayin.

    Still I had never paid any attention to the fact brought up in the OP, but now that I do....hmmmm.
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    Quote Originally Posted by kylebce View Post
    Good points by RamRod.
    Most pistol cartridges have been around a long while. The 9mm, .38 & .45 were all used in WW2. Full metal jacket is the Geneva Convention rule in combat.
    The correct reference is the Hague Convention of 1899, Declaration III. The Geneva Convention is about treatment of POWs.
    A common misconception.
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