The Remington Model 550 rifle is a rimfire …

variants:

• • • • Remington Model 550-1
      • Remington Model 1A
      • Remington Model 550-2G ‘Gallery Special’
      • Remington Model 550-A

gunsmithing note(s):

• • • If the sear spring case becomes cross-threaded due to improper disassembly and/or assembly, the threads are 3/8-32.¹
    • . . .

document(s):

• • • The Remington Model 550 & variants appear on page 632-5 of the Encyclopedia of Modern Firearms. This includes references to the Remington Model 550-2G ‘Gallery Special’, sectional views of the Remington Model 550-1 with the action open and the action closed, sectional views of the Remington Model 550-A with the action open and the action closed, a sectional view of the Remington Model 550-2G with the action open, general disassembly instructions, some troubleshooting guidance, and a parts list.²

1. I have fixed more than one of these.
2. Brownell, F. R. Encyclopedia of Modern Firearms. Brownell, 1959.