From 1920 to 1945 the Peso contained 0.720 fine silver which equates to 0.3856 ounces of silver each. From 1947 to 1949 the fineness was reduced to 0.500 fine silver so they have only 0.225 ounces of silver each. In 1950 the silver alloy was 0.300 fine (0.1285 oz). From 1957 to 1967 it was cut to 0.100 fine (0.0514 oz).
So be careful which dates you buy as bullion items. In the space of less than 50 years 1914 to 1957 the silver content of the Peso went from 0.7859 oz to 0.0514 oz and then to NOTHING.