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What makes AP rounds Armor piercing?

Discussion in 'General Gun Discussions' started by nsf003, May 7, 2003.

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  1. nsf003

    nsf003 Member

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    I hear everything about how APs can cruise through vests, steel plates, etc...

    What metal is used to make APs? I would think that steel would do a pretty good job at piercing stuff, lot of steel core ammo around. I could be wrong. Or copper for that matter. What is in that stuff, titanium?

    Is just the tip AP or is the whole bullet made of this magical metal?

    What's better, a lighter or heavier bullet?

    Are they legal in PA?(or anywhere)

    nsf003
     
  2. Jerrywahid

    Jerrywahid Member

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    I think whatever the metal is the principle is a matter of combining density and structural integrity. The integrity is neccessary so that when it hits the armor it doesn't deform and lose critical armor piercing energy. I am not answering your original question I guess. Sorry.
     
  3. Ian

    Ian Member

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    The penetration of an AP bullet comes from its hardness (primarily), as well as density and shape. Most of them are steel (the harder-tempered, the better). When a normal lead bullet hits armor it deforms, absording its own kinetic energy in the process. The energy required to deform the steel core of an AP bullet is much higher than lead, so while the lead outer layer will "splat," the core will continue unchanged, forcing the armor to deform. Density aids penetration, as it gives the penetrator more kinetic energy, assuming equal velocities. A small frontal area also aids penetration by concentrating energy on a small point.

    Tungsten has also been used for AP cores, as has uranium (though uranium is mainly used for its density).

    I believe that lower mass/higher velocity is better for penetration.

    The penetrator cores are located in different places in different bullets. The best is at the rear, as this allows the lead front of the bullet to keep the core in alignment as it enters the armor.

    I know AP rifle ammo is legal Federally; I don't know about PA law.
     
  4. QuarterBoreGunner

    QuarterBoreGunner Member

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    The 5.7x28mm SS190 round developed by FN for the P90 and Five seveN pistol is sorta AP. What I mean is that the round itself has a steel jacket with an aluminum core, with an airspace at the tip to impart tumble in terminal ballistics.
    It was designed to defeat pretty much any kind of body armor but lose velocity drastically after about 200m.

    They got it half right. The round will defeat up 48 layers of aramid/kevlar and up to 2mm of Krisat armor (within that 200m envelope) but is extremely over penetrative in terminal ballistics and exhibits little, if any, yaw or tumble, creating through and through wounds.

    I hope they (FN) get it right, because the P90 system is a sweet rig, and I'd hate to see it hobbled by a under performing round.
     
  5. Andrew Wyatt

    Andrew Wyatt Member

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    sectional density and velocity determine the penetrative capability of a round.


    weight isn't a factor.

    the main reason they only allow military calibers at the SWAT world championship 3 gun match is things like .243, .270, and the 6.5mms have enough sectional density and velocty to punch holes in the plates that stop .308 and .30-06 ball with no problem.

    we did some tests with fast 100 grain .308 bullets and 100 grain .243, and the .243 put holes in the plates. .308 didn't.
     
  6. Stevie-Ray

    Stevie-Ray Member

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    Generally Tungsten carbide cores in the AP surplus that we used to be able to buy. .308, .30-06, etc. Nationally illegal now, I believe.
     
  7. gun-fucious

    gun-fucious Member

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    II. Laws

    G. Federal Fireams Laws

    1. Federal Law and Armor Piercing Ammunition
    by James O. Bardwell (bardwell@netcom.com)



    ++++++++++++++++++++++++++++++++++++++
    WHAT IS AP AMMO, BY FEDERAL LAW?

    The definition of AP ammo is at 18 USC sec. 921(a)(17):
    "(B) The term `armor piercing ammunition' means-

    (i) a projectile or projectile core which may be used in a handgun and
    which is constructed entirely (excluding the presence of traces of other
    substances) from one or a combination of tungsten alloys, steel, iron, brass,
    bronze, beryllium copper, or depleted uranium; or

    (ii) a full jacketed projectile larger than .22 caliber designed and
    intended for use in a handgun and whose jacket has a weight of more than 25
    percent of the total weight of the projectile.

    (C) The term `armor piercing ammunition' does not include shotgun shot
    required by Federal or State environmental or game regulations for hunting
    purposes, a frangible projectile designed for target shooting, a projectile
    which the Secretary finds is primarily intended to be used for sporting
    purposes, or any other projectile or projectile core which the Secretary
    finds is intended to be used for industrial purposes, including a charge
    used in an oil and gas well perforating device."

    [Secretary means Secretary of the Treasury, in reality determinations
    are delegated to the Technology Branch of the Bureau of Alcohol, Tobacco
    and Firearms (ATF)]

    Note the following things from the definition:

    1) The definition was changed as part of the 1994 Crime Bill (9/14/94),
    primarily by the addition of "full jacketed" bullets intended to be used
    in a handgun whose jacket is more than 25% of their weight. The previous
    language is at the end of this article, for comparison purposes.

    2) AP ammo is the bullets ONLY, not the loaded ammo, although ATF has
    identified some AP ammo by the loaded ammo, not projectiles, for the
    information of FFL dealers, who are not supposed to "willfully"
    transfer AP ammo.
    >From this it follows that loading the bullets identified above into
    completed rounds does not constitute "making" AP ammo; making the
    bullets themselves does.

    3) USE - The bullet must be able to be used in a handgun. Rather than
    construing this to mean regular handgun calibers, ATF construes this to
    mean any caliber for which a handgun has been made, including handguns
    in rifle calibers, like .308 Winchester, and 7.62x39, for purposes of
    bullets covered by (B)(i). Thus bullets suitable for these calibers,
    as well as other rifle calibers for which handguns have been made (at
    least commercially made) which are constructed as described below would
    or should be AP ammo.
    However bullets that fall into the AP definition under (B)(ii), because
    their jackets comprise more than 25% of their weight (solid copper bullets?)
    must be intended for use in a handgun, not just be able to be used in a
    handgun.

    4) CONSTRUCTION - The bullet must either have a core made ENTIRELY out
    of one or more of the listed metals, or be a full jacketed type bullet
    with a jacket comprising more that 25% of its weight. Thus SS109/M855
    .223 (5.56mm) bullets would not be covered, because their core is only partly
    steel, and partly lead. Lead is not a listed metal, and bullets with
    cores made partly out of lead are OK. ATF has expressly ruled that
    SS109/M855 bullets are not covered.

    5) Hardness of the bullet is irrelevant.

    6) Ability to actually penetrate any kind of soft body armor is irrelevant.

    ATF has listed the following rounds as AP ammo:

    All KTW, ARCANE, and THV ammo.
    Czech made 9mm Para. with steel core.
    German made 9mm Para. with steel core.
    MSC .25 ACP with brass bullet.
    BLACK STEEL armor and metal piercing ammunition.
    7.62mm NATO AP and SLAP.
    PMC ULTRAMAG with brass bullet (but not copper).
    OMNISHOCK .38 Special with steel core.
    7.62x39 ammo with steel core bullets.

    ATF has specifically exempted the following rounds:

    5.56 SS109 and M855 NATO rounds, with a steel penetrator tip.
    .30-06 M2 AP ammo.

    WHAT FEDERAL RESTRICTIONS ARE PLACED ON AP AMMO?

    If you are NOT a (FFL) licensee under the Gun Control Act (an individual):
    It is: ok to OWN AP ammo
    ok to SELL AP ammo
    ok to BUY AP ammo
    ok to SHOOT AP ammo
    NOT ok to MAKE AP ammo (18 USC sec. 922(a)(7))
    NOT ok to IMPORT AP ammo (18 USC sec. 922(a)(7))
    The only persons who can make AP ammo are holders of a type 10
    FFL, also needed to make destructive devices, and ammunition for
    destructive devices. The only persons who can import AP ammo
    are holders of a type 11 FFL, who can also import DD's and ammo
    for DD's. The FFL's cost $1000 a year.

    If you are a licensed manufacturer or importer:
    NOT ok to SELL or DELIVER AP ammo (18 USC sec. 922(a)(8)
    (with exceptions for making/importing for law enforcement, export, or R&D).
    No additional restrictions, except as listed below. This applies
    not only to holders of type 10 and 11 FFL's, but also type 7 and 8
    FFL's (makers and importers of guns other than DD's), as well as
    holders of a type 06 FFL (maker of ammo other than for DD's).

    If you are a licensed dealer, manufacturer, importer or collector:
    NOT ok to SELL or DELIVER AP ammo without keeping a record of the sale, similar
    to the bound book record for firearm sales. (18 USC sec. 922(b)(5)).
    No additional restriction, except on dealers as noted below.
    The records required to kept on sale or delivery of AP ammo need only
    be kept for two years, not twenty years, like firearm records. See
    27 CFR sec. 178.121, and 27 CFR sec. 178.125.

    18 USC sec. 923(e) allows the revocation of a dealer's FFL
    for willfully transferring AP ammo, with exceptions for sales to law
    enforcement and so on. This is dealers only; holders of a collector
    FFL (type 03) may willfully transfer AP ammo if they wish, but must comply
    with the record keeping noted above.

    Some states also regulate or prohibit armor piercing ammo, and these
    laws may bear no relation to how the federal law works. For state
    laws, check locally. The following states regulate AP ammo,
    to my knowledge, but the definition of AP ammo and sort of
    regulation may (and likely does) deviate widely from the federal
    approach. NV, OK, RI, VA, AL, NY, NJ, IL, IN, KS, LA, MN, FL, PA, TX, NC.

    +++++++++++++++++++++++++++++++++++++++
    The former statute: 18 USC 921(a)(17)(B) - "The term 'armor
    piercing ammunition' means a projectile or projectile core which
    may be used in a handgun and which is constructed entirely (excluding
    the presence of traces of other substances) from one or a combination
    of tungsten alloys, steel, iron, brass, bronze, beryllium copper, or
    depleted uranium. Such term does not include shotgun shot required
    by Federal or State environmental or game regulations for hunting purposes,
    a frangible projectile designed for target shooting, a projectile
    which the Secretary finds is primarily intended to be used for sporting
    purposes, or any other projectile or projectile core which the
    Secretary finds is intended to be used for industrial purposes,
    including a charge used in an oil and gas well perforating device."
     
  8. SDC

    SDC Member

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    Normally, a combination of factors such as projectile (or core) hardness, and the velocity that the round is fired at will determine what makes an armour-piercing bullet pierce armour. There ARE a couple of ballistic "tricks" you can do to make a bullet MORE penetrative though; if you make the frontal area of a bullet as small as possible (ie. you make it pointed), it will have an easier time during the initial penetration, and its retained energy will carry it through into the target. The THV rounds below (the machined bronze "spire point" ones) are an example; by concentratig all of their force on the "needle" point, they're more likely to find a way through Kevlar weave. HTH.
     

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  9. Jeeper

    Jeeper Member

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    Sweet picture
    :what:
     
  10. 280PLUS

    280PLUS Member

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    nothing friendly looking about those...

    boy, we got some smart people around here...

    :D
     
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