The CMP advises to not use .30/06 ammunition in M1 Garands, 1903s, and 1903A3s that is loaded beyond 50,000 CUP and has a bullet weight more than 172gr. These rifles are at least 70 years old and were not designed for max loads and super heavy bullets. Always wear hearing and eye protection when firing an M1 Garand, 1903 and/or 1903A3 rifle.
This warning is an update/addition to the Ammunition section in the Read This First manual enclosed with each rifle shipment (M1 Garand manual-page 6 and M1903 manual-page 10).
Civilian Marksmanship Program