Abstract: An ammunition magazine for small arm weapons having a reciprocating bolt and an ammunition feedwell therein includes a housing for storing a plurality of ammunition rounds and a drive spring for urging the ammunition rounds out of the housing. In addition, a feeder is provided for passing the ammunition rounds from the housing into the ammunition feedwell of the small arm weapon. The feeder is configured for being removably inserted into the small arm weapon ammunition feedwell and includes a feeder spring for urging ammunition rounds along the feeder from the ammunition housing and within the ammunition feedwell. An impact system is provided for engaging the reciprocating bolt of the small arm weapon and causing movement of the reciprocating bolt to compress both the drive spring and the feeder spring.