Mark 2 was constructed of tube, jacket and two hoops.  Mark 3 was nearly the same with some minor differences in the recoil cyclinders and a larger muzzle bell.  Mark 4 was similar to the Mark 3 but with a modified groove for the yoke.

One of the Mark 3 Mod 3 guns was cut down to 25 calibers and used to test anti-aircraft concepts at the proving grounds.  This led to the later development of the successful 5"/25 (12.7 cm) Mark 10 AAA weapon.

USS Olympia C-6 in 1899 flying the four-star flag of Admiral George Dewey
The 5"/40 (12.7 cm) guns are in the superstructure casemate mounts
Olympia was later rearmed with 5"/51 (12.7 cm) guns
U.S. Navy Historical Center Photograph # NH 2894

5"/40 (12.7 cm) guns aboard Auxiliary Cruiser USS Saint Paul in 1898
These are in Center-Pivot mountings
U.S. Naval Historical Center Photograph # NH 89086

5"/40 (12.7 cm) gun aboard USS Henry R. Mallory (ID-1280) in 1918-1919
This appears to be one of the later Pedestal mountings
U.S. Naval Historical Center Photograph # NH 103295

Gunner Shaw and his 5" (15.2 cm) gun on USS Raleigh (C-8)
This gun is credited with firing the first shot during the Battle of Manila Bay in 1898
Detroit Publishing Company Collection Photograph
Library of Congress Photograph ID LC-D4-20916