Took my M&P15 out the other day and the son and I put 160 rounds through it. We had 100 rounds of American Eagle and 60 rounds of Winchester FMJ. The headstamp on the American Eagle is what looks like crosshairs in a circle and then LC 13. Would this be Lake City, 2013. The Winchester ammo has the same crosshairs but has WCC (Winchester Cartridge Co?) and 13.

The circle/cross is the head stamp for NATO spec ammunition

LC is Lake City who may have only supplied the brass that was then loaded by American Eagle.

American Eagle is Federal. Federal is ATK. ATK is the operator of the Lake City Ordnance Plant. It isn't too hard to understand that if Lake City currently has excess capacity for its' military contracts and Federal has a market for the excess they would market it under their American Eagle brand.

Olin/Winchester also has military contracts, see above. They sell the excess as WWB.

Thanks, Learned a lot.