Cabela's offers some really great deals on .223/5.56 ammo. Mix & Match to get to $99 total order and use coupon code 2FALL for $5 S/H.

Federal American Eagle .223 LCT (Lake City tipped bullet) Rifle Ammunition - $6.99 + $5 S/H over $99

PMC X-Tac Rifle Ammunition 55gr - $6.99 + $5 Shipping over $99

PMC Bronze 223 Rem 55 gr FMJ BT 20 Rnds/bx - $5.99 + $5 S/H over $99

MFS .223 Rem 55-Gr. FMJ 20 Rnds - $5.49 + $5 S/H over $99

Herter's .223 Ammunition with Dry-Box 500 Rounds - $134.99 + $5 S/H