The German 28 cm K5 (E) has an unconfirmed range of 31 miles and fires a pre-engraved projectile weighing approximately 550 pounds. It is fired from a turntable affording a 360° traverse.
The gun has a 70-foot 8-inch barrel held in a sleeve-type cradle. The barrel recoil mechanism, fitted between two arms projecting downward from the cradle, consists of two hydropneumatic cylinders and a single hydraulic buffer cylinder. The cradle is supported by trunnions which rest in bearings on top of a box-like frame, of girder construction, which in turn is supported on two pintles resting in bearings in the center of two 12-wheel trucks. The front pintle bearing rides in a rail on the front truck and can be positioned six inches either side of center, thereby allowing a car traverse of approximately 1°.
The equipment in effect has a double recoil action. Besides the barrel recoil which is approximately 32 inches, the gun car recoils. It is coupled to the front of the turntable platform by a hydraulic buffer and a hydropneumatic counterrecoil mechanism which returns the car to battery position.
A turntable platform is transported as part of the equipment and in transport forms a flat car with a 103-foot bed resting on two 8-wheel trucks.
A central jack helps support the tremendous weight of the gun and carriage which amounts to around 230 tons and also serves as a central pivot for the turntable.
The powder chamber is approximately 10 feet 5 inches long. Obturation is obtained by means of a short brass cartridge case and the breech is closed with a horizontal sliding type of breechblock. Firing is of the percussion type.
SPECIFICATIONS
| Caliber | 280 mm (11 ins.) | |
| Length of barrel | 70 ft., 8 ins. | |
| Length of tube | 67 ft., 5 ins. | |
| Length of rifling | 57 ft. | |
| Rifling | Right Hand uniform twist | |
| Weight of barrel (Leopold)* | 187,880 lb. | |
| Length of car | 95 ft., 7 ins. | |
| Length of carriage | 69 ft., 8 ins. | |
| Width of carriage (overall) | 8 ft., 8 1/2 ins. | |
| Number of grooves | 12 | |
| Width of grooves | 5/8 in. | |
| Depth of grooves | 17/64 in. | |
| Max. range | 54,680 yds.** | |
| Traverse on turntable | 360° | |
| Carriage traverse (approx.) | 1/2° R; 1/2° | |
| Elevation (estimated) | 50° | |
| Ammunition | Separate loading—steel splined projectile | |
| Weight of projectile (approx.) | 550 lb. |
*Two of these guns were found in Italy; one was called “Leopold,” and the other “Robert.” The weight of the barrel on the latter model is 187,165 pounds.
**Not verified.
German: p. 100.2