Batteries of these railway guns in concrete emplacements were found on both the Cherbourg and Brest Peninsulas in France. Equipment consisted of the gun, carriage, turntable, power plant and electrical operating unit, and ammunition car.
The piece is of the built-up type, consisting of a tube and two jackets. It is screwed into the breech ring. The breechblock is of the horizontal sliding wedge type. The hydropneumatic recoil system has two cylinders located under the carriage; the pistons are fastened to the lower end of the breech ring.
The carriage, when mounted on a turntable, has a traverse of 360 degrees; it is estimated that elevation is from 0 to 840 mils.The turntable, consisting of two sections bolted together, rotates on a central pivot and a portable circular track. Four wheels at each end of the turntable support it on the track. Electric motors are geared through these wheels to rotate the piece in azimuth. It is very similar to the 28 cm K. 5 (E) reported on page 100.2.
A small ammunition car, equipped with a removable roof, is mounted on trucks and runs on a two-rail track which is built in as a part of the turntable track.
SPECIFICATIONS
| Weight of gun | 45,500 lbs. | |
| Weight of carriage w/ gun | 189,000 lbs. | |
| Caliber | 203 mm (7.982 ins.) | |
| Weight (firing position) | 92.5 tons | |
| Length (traveling position) | 63 ft. (approx.) | |
| Height (traveling position) | 13 ft. | |
| Height (firing position) | ||
| Width (overall) | 13 ft. (approx.) | |
| Track | Std. railway gage 56 1/2 ins. | |
| Length of tube | 30 ft., 7 ins. | |
| Length of tube and breech | 32 ft., 8 1/2 ins. | |
| Length of rifling | 22 ft. | |
| Rifling | Uniform R.H. twist | |
| No. of grooves | 64 | |
| Width of grooves | 0.188 in. (approx.) | |
| Depth of grooves | .125 in. (approx.) | |
| Width of lands | ||
| Muzzle velocity (shell) | 2,800 f/s | |
| Range (est.) | 36,000 yds. | |
| Traverse (on turntable) | 360° | |
| Elevation (estimated) | 47° | |
| Depression | 0° | |
| Length of recoil (from recoil index slide) | 25 1/2 ins. | |
| Ammunition | APCBC, APBC, HE, Practice, Illuminating with parachute | |
| Wt. of projectile | 259 lbs. | |
| Wt. of propellant (max. charge) | 96.5 lbs. |
German: p. 102.1 (May 1, 1945)