Hey Tom, you might like these two manuals. TM 9-1270 Covers the 1903, 1903A1, 1903A3 and the 1903A4. The other one is: TM 9-1005-205-34. This one is specifically for the 1903A4. Tech Manual for support includes parts and special tools list, repair parts and special tools for the A4. I am sure many portions of it would also apply to the model you are interested in.