Irish, Your high school French has served you well. Acier special means special steel.
BigE, Your gun was made by Fabrique National in Belgium. FN made all the Browning A5s that were sent to the US starting in 1923 until they were produced in Japan by Miroku starting in 1976. The FN guns had different engraving and wood the the Brownings. Your gun may date from 1906 to 1938 ( may be exceptions). If you post the first few numbers of the serial number,we may be able to date the gun. Tell us more about the choke system. Is there an astrik marked on the barrel(* or ** or **-,etc.)? A detailed description is always the best route to any gun's history.