Below are some direct links to an OUTSTANDING FAQ from The Ammo Oracle at AR15.com.

It is a very comprehensive collection of information on .223 and 5.56 ammo.

The AR15.COM Ammo Oracle

History and Basic Design of .223 and 5.56 Ammunition.

• What is the history behind the development of the .223/5.56mm round?
• What is the difference between 5.56×45mm and .223 ammo?
• Which should I be looking for in an AR15, a 5.56 NATO or .223 Remington chamber?
• What is the circle-cross stamp on some of my ammo?
• How can I tell if a round is SAAMI, U.S. military, or 5.56 NATO Mil-Spec?
• What is FMJ? JSP? JHP? FMJBT?
• What is “Ballistic Tip” ammo?
• What types of ammo has the US Military used in its M16s and M4s?
• What about Mk262 or Mk262 Mod1?
• What are the dimensional specifications for M855 and M193 casings?
• What is SS-109? Is it the same as M855?
• What type of ammo is current issue for US Military forces?
• Why did the US Military adopt M855 for the M16?
• So why don’t all US military units carry M855?
• Is all SS-109/M855 ammo marked with green bullet tips?

Performance of .223 and 5.56 Ammunition.

• I have my rifle zeroed with M855 ammo. Will any 62gr ammo shoot the same?
• Do M193 and M855 shoot to the same point of impact?
• Ok, what is all this stuff about rifle twists and different ammo?
• OK, that’s complex. Simple question: Can I fire M193 ammo in my 1:7 or 1:9 twist barrel?
• Can I fire M855/SS-109 in my 1:12 twist barrel?
• Will M193 be accurate in a 1:7 or 1:9 twist barrel?
• What twist rate do I want for my rifle?
• 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?
• 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?
• Military ammo has flash retardant, right?
• What sort of velocity and ballistics should I expect from military ammo?
• Will Military Ammo wear my favorite National Match/Elite Sniper/$5500 accurized AR rifle out faster?
• What is Moly? What’s it good for?
• 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.

• So which ammo is better, M193 or M855? And what is all this discussion about fragmentation? Are these dum-dum bullets?
• So, velocity is a critical component for the wound profile. How fast must the bullet be traveling when it hits its target in order to fragment reliably?
• At what range will M193 fragment? How about M855?
• So do both M193 and M855 fragment the same? How do their wound profiles compare to the FBI requirements?
• Isn’t 7.62 NATO much better for long range penetration than 5.56 anyhow? Why would I want to use 5.56 when I could send 7.62 downrange instead?
• Didn’t tightening the twist rate from 1:14 to 1:12 reduce the wounding potential of M193?
• If I increase spin or barrel twist, won’t that decrease wounding by making a round more stable in tissue?
• Does the 2,700 fps rule apply to all .223 and 5.56 ammo?
• That’s really complicated. Simple question: Why is M193 better than M855?
• But doesn’t M855 penetrate hard objects better than M193?
• I heard that M855 has had serious stopping problems in Afghanistan, and earlier in Somalia. Is this true?
• Is military ammo the best choice for defensive use?
• But what about specialty commercial rounds, like TAP, hollowpoints and softpoints? Aren’t they better than Mil-Spec ammo for defensive use?
• Won’t JSP and JHP rounds be safer indoors? Don’t I have to worry about FMJ rounds going through walls and hurting my family or others?
• I’m concerned about roving packs of zombies driving automobiles after the end of the world as we know it. Since, as everyone knows, you have to make headshots to kill zombies, what ammo should I be using to defeat auto glass and sheet metal?
• So are heavier rounds dead for self-defense purposes?
• What about using Wolf in defensive roles?
• Will M193/M855 penetrate a bulletproof vest?
• My department is considering using 10″ or 11.5″ barrels for our ARs. They are so cool, and everyone knows that all the real go-fast, high-speed, low-drag operators use SBRs. Plus, Robert DeNiro uses one in “Heat.” What’s the best ammo to use to poke big holes in the bad guys with these?

.223 and 5.56 Ammunition Testing

• Is Gelatin testing accurate or what?
• Where can I find reviews of various types of ammo?
• Why should I test new-production ammo? It should work, shouldn’t it?
• How do I make a professional looking/sounding range/ammo report of some ammo I liked/hated?
• What is “B & T Ammo Labs?”

Selection of .223 and 5.56 Ammunition.

• Do I want SS-109 or M855 then?
• What if I want more punch? What should I move up to from 5.56mm?
• Isn’t 5.56 too dangerous to use indoors? Shouldn’t I use a pistol or shotgun instead?
• What is “SHTF” ammo? What is TEOTWAWKI?
• What is the best M193 to get?
• But aren’t all M193 rounds the same? It’s a standard specification, right?
• What is with this goo and the dings on my Lake City Rounds? What is this discoloration on the necks of my Q3131A? Did someone take a blowtorch to it?
• What is the best M855 to get?
• Where can I get some M995 AP?
• Should I leave two tracers at the bottom of my magazine to tell me when I’m out of ammo?
• Isn’t shooting tracers bad for my weapon?
• Can tracers cause fires?
• What is the best round for hunting deer-sized game?
• What is the best round for varmint hunting?
• What is the best round for match use?
• Will steel-jacketed bullets wear out my barrel?
• Is Wolf-brand (or other steel-cased) .223 ammo okay to shoot in my AR15?
• Are there any other factors that might cause me to avoid ammo?

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

• What ammunition does Troy recommend for self-defense, plinking, training and match use?
• What ammunition does Derek F. recommend for self-defense, plinking, training and match use?
• What ammunition does Tatjana recommend for self-defense, plinking, training and match use?

Purchase and Storage of .223 and 5.56 Ammunition.

• Where can I get military ammo, like M193 and M855?
• What brands of M193 are available?
• What brands of M855 are available?
• Where did all the South African Battlepack Ammo go?
• I’m buying ammo for long-term storage and I have found some surplus ammo cheap. Should I buy that?
• So what should I be paying for ammo?
• I chambered a round in my AR and then unloaded it later. The primer has a small dent in it, apparently from the firing pin. Should I be worried about this? Won’t that cause a slam-fire? Should I switch to a Titanium firing pin?
• How do I store ammo properly?
• Where can I buy ammo cans?
• What is a stripper clip?
• What is a bandoleer?
• Where can I buy stripper clips, guides, bandoleers and related items?
• What is “sealed” ammo? Why does it matter? How can I tell if my ammo is “sealed”?
• What common ammo is properly sealed? Is Wolf/SA/Lake City/M193 properly sealed?
• My wife just got one of those uber-cool vacuum food packers. I was thinking of sneaking into the kitchen and vacuum sealing all my ammo when she goes to watch the kids play soccer this weekend. What do you think?
• OK I’m hyperparanoid. Plus, vacuum packing is cool. Which vacuum packer should I use? How do I get started?
• Can I store ammo pre-loaded in magazines for an extended period of time? Won’t the magazine springs wear out and cause feeding problems? Shouldn’t I rotate my mags?
• Shouldn’t I be loading my mags with a few less rounds? If I load them to capacity doesn’t that cause reliability problems?

Legal questions.

• Isn’t against the Geneva Convention for the military to use hollowpoint or fragmenting ammo?
• Isn’t M855 ammo Armor Piercing (AP) and illegal to possess for non-law enforcement? Isn’t M855/SS-109 restricted to military/law enforcement use? Isn’t SS-109 illegal in Illinois?
• I am never going to use handload/law enforcement only/specialized rounds for self defense because that fact will be used against me in a criminal/civil proceeding to show I am a evil man/woman and be used to imprison/bankrupt me.