10 U.S.C. § 8327: Officers and enlisted members of the Navy Reserve and Marine Corps Reserve: 30 years; 20 years; retired pay

at least 30 years of active service in the armed forces, other than active duty for training; or at least 20 years of active service in the armed forces other than active duty for training, the last 10 of which he served in the 11-year period immediately preceding his transfer to the Retired Reserve. Each member who is transferred to the Retired Reserve under subsection (a) is entitled, when not on active duty, to retired pay at the rate of 50 percent of the basic pay of the grade in which retired. This section applies only to persons who were members of the Navy Reserve or the Marine Corps Reserve on January 1, 1953 . This section terminates on January 1, 1973 . However, its termination will not affect any accrued rights to retired pay. A member who is eligible for retirement under this section, and who is also eligible for retirement under another provision or for transfer to the Fleet Reserve or the Fleet Marine Corps Reserve under section 8330 of this title , is entitled to elect which of these benefits he is to receive.