Sheepdawg's correct on the headstamp. The EC shows it is from one of these plants, the 42 is the year produced:
Eau Claire Ordnance Plant, Eau Claire, WI - Operated by US Rubber Co using EC headstamp in August and September 1942 covering .30 carbine and .45 ACP cartridges
Evansville Ordnance Plant (Chrysler), Evansville, OH - Operated by Chrysler Corporation from June 1942 to April 1944 producing .30 carbine and .45 ACP cartridgess
I have some that spans from the 40's through the 70's and they all shoot fine with no failures. Just make sure there is no corrosion or discoloration/ deterioration showing on the case or bullet.
In fact there are 500 rounds headstamped from the 70's that is in my bugout box.