As a repeat 1630-tonner authorized in 1940, known at the time to shipmates as a Bristol (modified Livermore)-class ship, the specifications for Federal Shipbuilding & Dry Dock Co. hull no. 207, Buchanan reflected the characteristics of all Gleaves-class ships built there: Length Overall: 348' 3"
Extreme Beam: 36' 3"
Normal Displacement: 1,630 long tons
Draft: Mean: 13' 5"
Designed Complement: Officers, 11; Enlisted, 201
Designed Shaft Horsepower: 51,000
Designed Speed: 35 knots
Screws: Two
Rudder: One
Stacks: Two
At launch, Buchanan’s armament was typical for a mid-1942 Bristol-class destroyer, with four dual purpose 5-inch/38 cal. guns in gunhouses, a single quintuple mount between the stacks for 21-inch torpedoes, 20mm single Oerlikons replacing five of the six 0.50 cal. machine guns of earlier ships, plus a 1.1-inch quadruple “Chicago Piano” anti-aircraft gun to starboard in the waist.Primary: 4 x 5-inch/38 cal. in four single mounts
Long-range anti-aircraft: 4 x 1.1-inch cannon in a single mount
Short-range anti-aircraft: 5 x 20mm Oerlikon in single mounts
Torpedo Tubes: 5 x 21-inch in one quintuple mount
ASW: 2 racks for 600-lb. charges; 4 “K”-guns for 300-lb. charges
Her electronics were also typical of the period just before SG (surface search) radar became available: Buchanan did not return to the United States for overhaul until the summer of 1944, but apparently received upgrades while deployed in forward areas. These modifications included an SG radar set, replacement of the 1.1-inch mount aft with a 20mm single Oerlikon. Forward, she received a centerline 20mm mount on a platform constructed forward of the bridge, plus two more—one on each side—on the after corners of the bridge wings. Thus her late 1943–early 1944 armament was as follows: Primary: 4 x 5-inch/38 cal. in five single mounts
Short-range anti-aircraft: 9 x 20mm Oerlikon in single mounts
Torpedo Tubes: 5 x 21-inch in one quintuple mount
ASW: 2 racks for 600-lb. charges; 4 “K”-guns for 300-lb. charges
When Buchanan returned to Bremerton in 1944 for her only overhaul of the war, her after 20mm singles were replaced by director-controlled 40mm twin Bofors: It appears no other modifications were undetaken at this time and Buchanan retained the following armament through the end of the war: Primary: 4 x 5-inch/38 cal. in five single mounts
Long-range anti-aircraft: 4 x 40mm Bofors in twin mounts
Short-range anti-aircraft: 7 x 20mm Oerlikon in single mounts
Torpedo Tubes: 5 x 21-inch in one quintuple mount
ASW: 2 racks for 600-lb. charges; 4 “K”-guns for 300-lb. charges
| 
