I've been researching the two remingtons today and it turns out I have a .32 and a .380! They were designed by John D. Pederson. "Approximately 64,796 Model 51s were made: 54,518 in .380 caliber, and 10,278 in .32. The .380 wes designated the “Series of 1918.” The .32 version didn’t appear until 1921, and was designated the “Series of 1921.”