Known. A solid bronze cannonball, of about four pounds, was still whole.
It was found outside the Alamo Church, in San Antonio, Texas. It lay about three feet down, in soil the diggers link to the battle of 1836. The page says the Mexican army mostly used bronze balls, and the Texan side mostly used iron ones. Four broken pieces of exploding shot were also found outside the church. Three of those pieces are bronze and one is iron.
The page says it is not certain the whole ball came from the Mexican army.
https://www.ancient-origins.net/news-history-archaeology/alamo-cannonball-discovery-00102617