The AR15.Com Ammo Oracle

History and Basic Design of .223 and 5.56 Ammunition.

Performance of .223 and 5.56 Ammunition.

Terminal Performance of .223 and 5.56 Ammunition.

.223 and 5.56 Ammunition Testing

Selection of .223 and 5.56 Ammunition.

Ammunition recommendations from the authors of the AR15.com Ammo-Oracle.

Purchase and Storage of .223 and 5.56 Ammunition.

Legal questions.

Miscellaneous .223, 5.56 and Other Ammunition Questions.

Ammo Oracle

Q. That's really complicated. Simple question: Why is M193 better than M855?

In a nutshell: Advantages of M193 over M855:

  • It costs less, so you can buy more.
  • It's compatible with any rifling twist.
  • It's generally more widely available.
  • It has a slightly flatter trajectory with the appropriate battle zero.
  • It appears to have better terminal ballistics than M855.
  • Though it isn't a bad idea to keep a couple of magazines worth of M855 in case you need to make a long-range (300+ yards) shot against a "hard" target (a vehicle or other equipment), most folks are better served with M193 for general use.

    Counter Opinion: Many optics (like some of the full size ACOGs) are calibrated to the ballistics of the 62gr M855 round, not the 55gr M193 rounds. Granted this is only a slight difference inside of 300 meters, but it will compromise the zero at longer ranges.


    Counter Opinion: Keeping two kinds of ammo is rather foolish. It just leaves the opportunity open for confusion during a crisis, when it's most important to keep things simple.


    Fact: Some penetration stats for M193 and 7.62 (M80): Thickness of material for positive protection against caliber ammo listed. Concrete (5,000 psi), 5.56: .5 inch, 7.62 and 30 cal, 7 inches. Wet sand, 5.56: 25 inches, 7.62 and .30, 36 inches. Packed or tamped earth, 5.56: 32 inches, 7.62 and .30: 48 inches.