Due to the small amounts of silver available, the first coins used by the early Republic c. 280 BC were made of bronze. This likely occurred as Roman conquered central Italy where bronze was plentiful. The coins of the period were cast, not struck. Aes Grave were nothing like the Greek coins that had been struck for the previous 350 years. The coinage was based on the libral standard where the As referred to a coin and the weight. One As equaled one Roman pound (or twelve uncia (ounces). The weight standard changed around 265 BC when the As equaled 10 uncia. This period was known as the light libral standard. 

Aes Grave coinage are normally quite crude looking based on their method of production. The imagery on the coins is typically simplistic in nature. Aside from the Romans, early Etruscan coinage is similarly cast. Other cast coinage types can be found in ancient Olbia however they are large and thinner in fabric.