BEST CHOICES FOR SELF DEFENSE AMMO. This
is hopefully going to answer all your questions about what ammunition to
pick for your rifle, pistol, or shotgun. Lists of well-performing
ammunition are provided.
THE AMMO ORACLE - The original resource to learn about the .223/5.56 caliber, its history, development, and caveats. Even though it mostly centers around M193/M855 and omits some of the newer OTMs, it is a great read and everyone should go through it at least once. There's also a downloadable PDF version, although it may not be completely up-to-date. For the most complete line-up of CURRENT ammo recommended for self-defense, please refer to the post "BEST CHOICES FOR SELF-DEFENSE AMMO".
AMMUNITION REVIEW AND REFERENCE. Refer to this post for information about commercially available ammo. Reviews are generated by readers, and a ranking is provided to help you pick out the wheat from the chaff. By clicking on the link for each reviewed ammo type, you can read the reviews and find out the good and bad points that have been reported.
COLLECTED POSTS BY MOLON - THIS POST IS A MUST-READ. Arfcom member Molon
has authored some incredibly informative posts about all kinds of ammo
with detailed information about sighting in, shooting groups, accuracy, velocity, etc. There is a lot
of information about the various heavy OTMs as well. This post pretty much deserves its own FAQ.
THE BOX O'TRUTH - Arfcom's own Old_Painless's website. Practical information for what happens when you shoot various things with different bullets. A very informative website - please make sure to check it out.