"This report is an effort to summarize design information used in the design of the Recoil Mechanism XM37 for the Howitzer, light, towed, 105mm: XM102 and the XM39 Recoil Mechanism for the Howitzer, light, self-propelled, 105mm: XM104 and in past designs of other standard hydro-pneumatic recoil mechanisms. The military characteristics required that the weapons be designed on a basis of proven state-of-the-arts. Therefore, much of the design of either the XM37 or XM39 Recoil Mechanism was based on the design of conventional hydro-pneumatic recoil mechanism. Both the XM37 and XM39 Recoil Mechanisms were the dependent type; however, the design information in general would also apply to the independent type hydro-pneumatic recoil mechanisms."--Page 1.

"December 1963"--Title page. "O.M.S. Code No. 5520.12.427C0.01.01"--Title page.

Summary --Introduction -- Procedure -- Recoil cylinder assembly -- Recuperator cylinder assembly -- Total geometry -- General topics -- Prefiring tests -- Static seals -- Wipers -- Threads -- Development of hydraulic packings -- Recoil mechanism oil -- Hydraulic cylinders -- Free recoil -- Life of a recoil mechanism -- Oil emulsification -- Assembly of a recoil mechanism -- Limiting design factors -- Firing tests -- Firing mounts -- Instrumentation -- Appendix.