I found this website that checks most of the major Ammo websites, and updates every 90 seconds. I have found a couple times where the vendor was out of stock, but not many.
http://www.gunbot.net/index.php?cal=223556
Calibers: .223, 7.62, .22, 9mm, .308
Websites checked:
ABLEAMMO
AIMSURPLUS
AMMOBANK
AMMOMAN
AMMOTOGO
BROWNELLS
BULKAMMO
GRAF
LUCKYGUNNER
MIDWAYUSA
NATCHEZ
OUTDOORGEARBARN
PALMETTO
SGAMMO
SPORTSMANSGUIDE
WHOLESALEHUNTER
WIDENERS
http://www.gunbot.net/index.php?cal=223556
Calibers: .223, 7.62, .22, 9mm, .308
Websites checked:
ABLEAMMO
AIMSURPLUS
AMMOBANK
AMMOMAN
AMMOTOGO
BROWNELLS
BULKAMMO
GRAF
LUCKYGUNNER
MIDWAYUSA
NATCHEZ
OUTDOORGEARBARN
PALMETTO
SGAMMO
SPORTSMANSGUIDE
WHOLESALEHUNTER
WIDENERS