5.56mm (.223) PARAMILITARY AMMUNITION

          The following article is from the January/February, 1988
          issue of Rifle magazine pages 36, 37, 70 and 71. This
          article was written by John Schaefer.

     Anyone who has shot firearms equipped with oversized magazines knows
the rate of ammunition expended is directly proportional to the magazine
capacity. As the popularity of assault rifles has increased, the need for
reasonably priced ammunition has skyrocketed, creating a market for what is
known as paramilitary ammunition.

     Western countries use 7.62x51mm and 5.56x45mm ammunition for their
official military rounds, so most paramilitary rifles are offered in those
calibers. With the adoption of the new SS109 5.56x45mm round as NATO's
standard small caliber rifle cartridge, there is a great demand for that
ammunition to feed all the rifles now available to the public.
Advertisements for "NATO-type ammunition" are now quite common, though the
ads are misleading as the ammunition does not meet NATO specifications.

   Any cartridge that does not have the cross and circle (+) in its
headstamp is not NATO approved, no matter what the ads say. Real NATO
ammunition must be manufactured under NATO surveillance and be certified to
meet strict requirements for velocity, chamber and port pressure, barrel
time, temperature stability, barrel erosion, waterproofing and other
characteristics. Furthermore, NATO ammunition must be produced by a
specified facility in a NATO country. Ammunition made by surrogate nations
cannot carry the NATO symbol or interchangeability code. An item often
overlooked is that M193 Ball 5.56mm ammunition cannot be NATO approved,
since the official NATO round is the SS109 (U.S. M855) cartridge, and only
7.62mm Ball ammunition with a 146 to 148 grain boat tailed bullet, such as
the U.S. M80 Ball or Canadian C21, could be considered for NATO
certification. That does not mean there is anything wrong with available
paramilitary ammunition. As thousands of shooters can attest, it is safe
and serviceable.

     Because the standard military rifle cartridge of the free world is
fast becoming the 5.56mm round, this article will deal with its
paramilitary versions.

     U.S. military specifications for M193 Ball ammunition require a 55
grain bullet (q 2 grains) at a muzzle velocity of 3,250 q 40 fps from a 20
inch test barrel measured 15 feet from the muzzle. The accuracy requirement
from a test fixture calls for a maximum of a two inch mean radius at 200
yards from ten 10 shot groups (which equates to approximately three MOA).
"Statistically average" M193 ranges from 1.2 to 1.6 inches mean radius,
which is equivalent to 1.8 to 2.4 MOA. Velocity from an M16 rifle or
pressure test barrel usually runs about 3,200 fps due to gas loss through
the port. Accuracy is typically around 2 to 2+ MOA from an M16A1 rifle at
ranges of 100 to 300 yards. M193 ammunition is suitable for use in 1 twist
in 12 inches or faster twists. While commercial sporting rifles in this
caliber usually have one in 14 rifling, the M193 boat tailed bullet is
barely stabilized with that rate of twist at ambient temperatures, and will
not stabilize at all when the air temperature drops below freezing.

     NATO specifications for SS109 (U.S. M855) Ball require a 61.7 grain
(q 1.5 grains) with a hardened steel penetrator at a velocity of 3,025 fps
(q 40 fps) from a 20 inch barrel 25 meters from the muzzle. Typical
velocity 15 feet from the M16A2's muzzle is around 3,100 fps. The accuracy
requirement from a test fixture equates to a maximum of approximately four
MOA over the 100 to 600 yard range. Typical accuracy of average lots in an
M16A2 is about 2+ MOA. This round must also penetrate a nominal 10 gauge
SAE 1010 or 1020 steel test plate at a range of at least 570 meters (623
yards). The M193 round will penetrate this same plate reliably at 400
yards, and about half the time at 500 yards. The 5.56mm and 7.62mm NATO
rounds will penetrate it reliably out to 700 yards or more. Nominal
ballistics for M193 and M855 Ball rounds are given in an accompanying
table. The tables were constructed from the latest data supplied by the
U.S. Army Ballistic Research Laboratory at Aberdeen Proving Ground,
Maryland.
              5.56 NATO Ball Ammunition Ballistic Comparison
                   based on Aberdeen Proving Ground Data
       velocity (fps)    trajectory (in.)  drop (inches)  drift (inches)*
 range   M193   M855       M193  M855      M193   M855     M193    M855
(meters)
  0      3,200  3,100     -2.5   -2.5       0.0    0.0      0.0     0.0
100      2,774  2,751     +2.8   +4.4      -2.2   -2.3      1.3     1.1
200      2,374  2,420     +2.7   +5.8      -9.9  -10.2      5.8     4.9
300      2,012  2,115     -4.9    0.0     -25.1  -25.3     14.2    11.8
400      1,680  1,833    -23.0  -15.0     -50.8  -49.5     27.6    22.4
500      1,373  1,569    -56.2  -42.9     -91.6  -86.7     47.5    38.0
600      1,106  1,323   -113.1  -88.2    -156.1 -141.3     76.4    59.5
700        995  1,106   -206.8 -156.1    -257.3 -220.9    113.5    88.4
800        927  1,010   -339.9 -267.7    -398.0 -339.2    156.1   124.9

                                                   * Drift for 10 mph wind.
M193 Ball ammunition fired in M16A1 rifle with 250 meter battle sight zero.
M855 Ball ammunition fired in M16A2 rifle with 300 meter battle sight zero.
____________________________________________________________________________

                      5.56mm Velocities and Accuracy

ammunition
55 grain Ball bullets
U.S. M193 "TW 73"
Lot TW-2-699
PMC M193
"PS 80"
Lot PS-E5-2139-79

     Because the steel penetrator increases the length and changes the
weight distribution of the SS109 bullet, it is suitable for use only in
barrels with a twist of one turn in nine inches or faster. Pre-1986 Ruger
Mini-14's with the one in 10 inch twist will handle this round but
stability is marginal and accuracy falls off below zero degrees Fahrenheit.
Military rifles intended to use this ammunition have a seven inch twist to
ensure bullet stability under arctic conditions and to stabilize the even
longer L110 and M856 tracer bullets. Current production Mini-14's and some
Ranch Rifles now have seven inch twists.

     To set the baseline for testing, U.S. M193 Ball was fired from both an
AR-15 (12 inch twist) and an AR-15-A2 HBAR (seven inch twist), to establish
velocity and accuracy standards. No M855 was available, as that ammunition
is restricted to U.S. government agencies.

     The Hirtenberger SC ammunition tested in the AR-15-A2 came from an
initial lot supplied by Hansen Cartridge Corporation. It is suitable for
nine inch or faster twist barrels, and was included for comparison.

     The IMI 223-13CL 63 grain softpoint load was included in the tests
since it is currently the only 5.56mm round with a heavy bullet readily
available. While it is usable in twelve inch twist barrels because of the
bullet's flat base and short overall length, it is sure to find favor among
owners of AR-15-A2's.

     Paramilitary 5.56mm ammunition should not be fired in commercial
rifles with chambers reamed to SAAMI specifications. The SAAMI chamber used
in sporting firearms has a smaller diameter bullet seat, a shorter throat
and less free bore than military chambers. Chamber pressures can rise
dramatically when military ammunition is fired in them.

     SAAMI specifications for commercial .223 ammunition specify an average
chamber pressure of 52,000 CUP. When military ammunition is fired in the
SAAMI chamber, pressures may rise to 55,000 or 60,000 CUP!

     U.S. manufactured paramilitary ammunition intended for civilian
consumption is purposely loaded down to SAAMI pressure levels and bullets
are often seated deeper to accommodate the SAAMI chamber. Ammunition
certified to meet Mil-C-9963F (the military specification for M193 Ball) is
only available to U.S. government agencies and private security firms under
contract to provide security for U.S. government installations.

     Imported ammunition of that type is generally loaded to standard
military levels and should be fired only in firearms with military
dimensioned chambers. To the author's knowledge, the only U.S. manufactured
commercial firearms with military chambers are the Colt AR-15 series, the
Ruger Mini-14 and Ruger No. 1 rifles manufactured since 1986.