5.56mm NATO ammo is a hotter load than .223 ammo.
Horniday 5.56TAP is in a red box marked Tactical Application Police , not for use in .223 chambers.
There are different chamber reamers currently in use today. A barrel with a "Wylde" chamber was designed to handle NATO pressure loads while delivering better accuracy than a NATO chamber. The Noveske Match Mod O chamber is designed to offer 100% reliability while retaining maximum possible accuracy. The chamber body is slightly larger than the 5.56mm NATO minimum, but within the 5.56 NATO tollerance. the throat is redesigned for proper bullet alignment with the axis of the bore. This chamber was developed to fire MK262 Mod 1 on AUTO in hot enviroments.
There are two cartridges with a "heavy" bullet loaded to 5.56mm NATO pressure specs one is Horniday 5.56 TAP the other is Black Hills MK262.
Black Hills MK262 ammo (BC= .340) muzzle velocity is
Colt 14.5in barrel 2628
Colt 16in barrel 2712
Colt 20 in barrel 2830
Horniday 75 TAP5.56 T2 (BC=.352) muzzle velocity is
Colt 14.5in barrel 2627
Colt 16 in barrel 2713
Colt 20 in barrel 2821
The 5.56-mm ball M855 (A059) cartridge has a gilding, metal-jacketed, lead alloy core bullet with a steel penetrator. The primer and case are waterproof. The ammunition is linked by a disintegrating metallic split-linked belt for firing from the ammunition box. In an emergency, the M855 round can also be loaded and fired from the M16 20or 30-round magazine. It is identified by a green tip, has a projectile weight of 62 grains, and is 2.3 cm long. This is the NATO standard round. It is effective against personnel and light materials, not vehicles.
US Military Lake City Arsenal M855 SS109 Penetrator ammo. 62 grain with steel tipped penatrating core for combat use, firing at 3,025 f.p.s.
"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.
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
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.
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.
The SS109 5.56mm NATO cartridge is a second generation intermediate power round developed with 1970's technology. It is
significantly more powerful and effective than the U. S. M193 5.56mm ball round originally used with the M16 rifle. The new
SS109 cartridge propels a heavier 62-grain semi-armor piercing projectile at an initial velocity of 3,050 fps (924 mps).18 The
improved projectile contains a 10-grain .182 caliber hardened steel penetrator that ensures penetration at longer ranges.
Total cartridge length and weight are 2.26 inches and 182.0 grains, respectively. The increased length and weight of the new
SS109 projectile requires a faster rifling twist of one turn in seven inches to fully stabilize the new projectile in
flight.19 The predecessor M193 5.56mm, which used a projectile weighting only 55 grains, was only marginally stabilized with a
slower rifling twist of one turn in twelve inches. The new projectile can penetrate the standard NATO 3.45mm steel plate up
to a range of 640 meters (704 yds) and one side of the U. S. steel helmet up to a range of 1,300 meters (1430 yds).20 In tests
of barrier and fortification penetration however, the steel penetrator of the SS109 could not pierce any of the test building
"Always do the right thing, just because it is the right thing to do".
Bobby Paul Doherty