AR15.COM :: Ammo Oracle

History and Basic Design of .223 and 5.56 Ammunition.

Performance of .223 and 5.56 Ammunition.

Q. I have my rifle zeroed with M855 ammo. Will any 62gr ammo shoot the same?
Q. Do M193 and M855 shoot to the same point of impact?
Q. Ok, what is all this stuff about rifle twists and different ammo?
Q. OK, that's complex. Simple question: Can I fire M193 ammo in my 1:7 or 1:9 twist barrel?
Q. Can I fire M855/SS-109 in my 1:12 twist barrel?
Q. Will M193 be accurate in a 1:7 or 1:9 twist barrel?
Q. What twist rate do I want for my rifle?
Q. What about XM193 from Federal and Q3131a from Winchester? I have heard that some of these don't meet military specifications, particularly with respect to sealant on the necks and primers?
Q. Holy earache Batman! This Q3131A/Lake City XM193 is really loud and it launches a FIREBALL from my muzzle! Everyone at the range is looking at me now. What gives?
Q. Military ammo has flash retardant, right?
Q. What sort of velocity and ballistics should I expect from military ammo?
Q. Will Military Ammo wear my favorite National Match/Elite Sniper/$5500 accurized AR rifle out faster?
Q. What is Moly? What's it good for?
Q. Moly sounds hella-cool. I'm going to use it will all my rounds from now on!

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.

Q. I have my rifle zeroed with M855 ammo. Will any 62gr ammo shoot the same?

No.

While M855 uses a 62gr bullet, it is a longer bullet due to the steel penetrator in the front of the bullet core. Steel is less dense than lead, so more volume of steel is needed to end up with the same weight (mass). There is also a small air cavity in front of the penetrator, unlike a bullet with a solid lead core. Any non-M855/SS-109 62 grain ammo (such as Wolf and Federal's American Eagle 62gr FMJ offerings) will have a solid lead core, and the resulting bullet will be significantly shorter than an SS-109 bullet. That means you can expect trajectory and penetration performance to differ as well.