30.'06, 30.06 Springfield, or M2 Ball 

The 30.'06 , introduced in 1906 as a 150 grain spitzer bullet for the Model 1903 Springfield service rifle. It replaced the 30-40 Krag for the US Military. The 30.'06 is based upon the original 30.'03 cartridge. In 1925 the 30.'06 or M1 Ball was adopted by the US Army . In 1940 the M2 Ball replaced the M1 Ball. The 30.'06 was the standard rifle round for the US from WW1 through the Korean War. In the US this is one of the most popular hunting rounds and can be found anywhere ammunition is sold.

New Production Ammo can be found manufactured by practically everyone.

Surplus Ammo - Found all over the place. Some is corrosive. If corrosive make sure you follow corrosive ammo cleaning guidelines or you will corrode you rifle bore. Most brass is pretty much unloadable.

Reloading Dies are made by Dillon Precision , RCBS, Redding, and Lee Precision , to name a few.

Reloading components can be found at Huntington's, Midway USA , and the Wholesale Hunter , to name a few.

Brass - Almost all US manufactured ammo produces good once shot brass and components abound.