A short history of Argentine 11.43mm pistols and the Graf Spee rumour....Argentina bought some 1911's, then in 1927 contracted for the Sistema lic by Colt. Later they developed the Ballester-Molina pistol, which was 1911ish, but had a different lockwork and no grip safety. Shared barrels and mags only. The steel used in the Molina was probably US steel supplied to UK under lend/lease. Arg was neutral in WWII, but sold lotsa Molena's to UK. During the period in which these pistols were being made, some Argentine vessels were scuttled and may have been used in making steel for guns, but there's no specific indication of that. (The ship in the rumour, the Graf Spee, was sunk in Uruguay, so no material could have been in Argentine foundries)
I've searched and looked and hunted, and cannot find where this rumour started, although G Gordon Liddy is credited with promulgating it on his radio program. It was orginally put forth as evidence of the inferiority of the argentine pistol, but that mindset shows a distinct lack of understanding of metallurgy.