This is courtesy of a clause in the 2018 NDAA bill, HR 2810, which has passed the House, and directs the Secretary Of Defense to approve the transfer.

The Firearm Blog reports:

The United States House of Representatives has just passed their version of the 2018 National Defense Authorization Act (NDAA), and included within it is a provision that will mandate the release of all M1911 handguns currently in US Army inventory to the Civilian Marksmanship Program, for distribution to eligible US civilians. The new bill would overwrite the 2016 NDAA, which allowed for the release of 10,000 of the pistols, but did not mandate it. The text of Section 1064 of the 2018 NDAA is as follows:

SEC. 1064. TRANSFER OF SURPLUS FIREARMS TO CORPORATION FOR THE PROMOTION OF RIFLE PRACTICE AND FIREARMS SAFETY.

(a) In General.—Section 40728(h) of title 36, United States Code, is amended—

(1) by striking "(1) Subject to paragraph (2), the Secretary may transfer" and inserting "The Secretary shall transfer";