Halfdan Karlsen Alstad was born on 12 January 1882 in Trondheim, Sor-Trondelag county, Norway. He graduated from the "Krigsskolen" (military academy) in 1903 and was commissioned a "premiaerloytnant" (Lieutenant).

Promoted to Captain in 1915, Halvdan Alstad served in the Norwegian Army (1903 - 1949) as a "Kontroll Offiser" responsible for the inspection and acceptance of firearms, especially for the Kongsberg-Colten .45 pistols, that were manufactured at the Kongsberg "Vapenfabrikk" (weaponry plant) in Kongsberg, Norway.

On 25 March 1924, 150 Kongsberg M/1914 Colt .45 pistols (i.e., serial #4101 thru #4250), and stamped by "Kaptein" Halvdan Alstad, were delivered to the "Hoved Arsenalet" (head arsenal) in Kristiania, Norway […later re-named Oslo, Norway].

The majority of his Kongsberg-Colten inspection/acceptance marks can be found on the right side of the receiver slide, just under the year of manufacture. His "merke" (mark) is distinguished as his initials, "H A" with the H imposed over the A.

NOTE: There were two basic models of Kongsberg-Colts:

M/1912 (serial #1 thru #95) stamped: "COLT AUT. PISTOL M/1912"
M/1914 (serial #96 thru #32854) stamped: "11.25 m/m AUT. PISTOL M/1914"

Based on John Moses Browning's design of the Colt .45 semi-automatic pistol US Government Model 1911, manufacturing started at the Kongsberg Vaapenfabrikk in 1916. The first 95 pistols were delivered to the "Hoved Arsenalet" in Kristiania, Norway between 3 and 8 December 1917.

Production was halted at serial #32854 in 1947.