Well I see a couple I need to get.
Often mentioned are the Scott A. Duff books on the M1icon Garand. Joe Poyer's "The Model 1903 Springfield Rifle".
My last two were ".380 Enfield No.2 Revolver" by Stamps & Skennertonicon, and "The Handgun" by Geoffrey Boothroyd, which is out of print , but available at Abe Books.