Not sure about that many rounds, but smaller amounts see this from TSA.
Travelers should remain in the area designated by the aircraft operator or TSA representative to take the key back after the container is cleared for transportation.
Travelers must securely pack any ammunition in fiber (such as cardboard), wood or metal boxes or other packaging specifically designed to carry small amounts of ammunition.
Firearm magazines and ammunition clips, whether loaded or empty, must be securely boxed or included within a hard-sided case containing an unloaded firearm.
Small arms ammunition, including ammunition not exceeding .75 caliber for a rifle or pistol and shotgun shells of any gauge, may be carried in the same hard-sided case as the firearm, as long as it follows the packing guidelines described above.
TSA prohibits black powder or percussion caps used with black-powder.
Rifle scopes are not prohibited in carry-on bags and do not need to be in the hard-sided, locked checked bag.
The locked case must be a TSA style lock so it can be opened. Available everywhere.