I don't know that this is correct, but my understanding is that the St. Louis Arsenal records are missing/lost. I've read this with respect to the small cannon produced in St. Louis that required special ammunition (e.g. the Woodruff or Filley pieces used at Kirksville, Fort Davidson, Clarks Mill, Helena, etc.) There is no record of purchases of the ammo, so the theory is that the rounds were produced in St. Louis. These small guns fired lead projectiles, an abundant material in Missouri, so local manufacture seems likely. See the Turner Brigade website for more background on these pieces.