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. What is SS-109? Is it the same as M855?

SS-109 is Fabrique Nationale's (FN's) name for their 61.5 grain bullet with the steel penetrator in the nose and what they call rounds loaded with this bullet. (FN calls M193-type ammo "SS-92.") The US military's M855 round is loaded with the SS-109 bullet, though the US military has additional specifications that ammo must meet before it can be called M855. So, while all M855 is loaded with SS-109 bullets, all "SS-109 ammo" will not meet the M855 specs. For example, the British purposely underloaded some lots of their ammo in an effort to get their L85A1 (SA80) rifles to cycle properly. The ammo is still loaded with SS-109 bullets and labeled as SS-109, but it is nowhere near the M855 velocity specifications.

Diagram of M855 construction.