210mm Krupp Mortar M. 1910
Bulgarian designation : 
21см
скорострелна мортира
Д12 

German designation : 
21cm Mörser L/12 

Calibre : 
210mm L/12 

Weight of the barrel : 
2620 kg 

Weight of the breechblock : 
229 kg 

Weight of the shield : 
86 kg 

Weight of the carriage : 
3713 kg 

Weight of the pedrails : 
820 kg 

Weight in action : 
7380 kg
(with pedrails) – 6630 kg (without pedrails) 

Weight of the limber : 
450 kg
(empty) – 640 kg (loaded) 

Weight in marching order : 
8520 kg 

Weight of the pedrails wagon : 
1328 kg
(empty) – 3345 (loaded) 

Barrel length : 
2530 mm 

Land diameter : 
211 mm 

Groove diameter : 
214 mm 

Rifling 
length : 
1763 mm 
twist : 
from 32 to
18 calibres 

Barrel grooves 
number : 
64 
width : 
6.85 mm 

depth : 
1.5 mm 

Width of the lands : 
3.5 mm 

Height of the line of fire : 
1600 mm 

Battering charges : 
9^{th}
charge: 5.6 kg R.P. (3x25.5) + 50 g n.Gew.P. 71 8^{th}
charge: 5.2 kg R.P. (3x25.5) + 50 g n.Gew.P. 71 7^{th}
charge: 4.9 kg R.P. (3x25.5) + 50 g n.Gew.P. 71 6^{th}
charge: 4.3 kg R.P. (3x25.5) + 50 g n.Gew.P. 71 5^{th}
charge: 3.9 kg R.P. (3x25.5) + 50 g n.Gew.P. 71 4^{th}
charge: 3.5 kg R.P. (3x25.5) + 50 g n.Gew.P. 71 3^{rd
}charge: 3.2 kg R.P. (3x25.5) + 50 g n.Gew.P.
71 2^{nd}
charge: 2.9 kg R.P. (3x25.5) + 50 g n.Gew.P. 71 1^{st}
charge: 2.6 kg R.P. (3x25.5) + 50 g n.Gew.P. 71 

4.2
kg Wurfpulver (12x12x2) + 50 g n.Gew.P.
71 (only
for seven charges) 

3.82
kg Wurfpulver (10x10x1.5) + 20 g n.Gew.P. 71 (only
for Gr. 14 and 14 A) 

3.95
kg Wurfpulver (10x10x1) + 20 g n.Gew.P.
71 (only
for Gr. 14 and 14 A) 

Shells 


21cmGr. 96 
weight : 
120 kg –
charge 17.58 kg of Füllpulver
02 (Trotyl) 
length : 
839.1 mm 

fuze : 
Kz.
Bod. Z. 10 

muzzle velocity : 
367 m/s 

max. range : 
9400 m with
the 9^{th} charge 8900 m with
the 8^{th} charge 8500 m with
the 7^{th} charge 

21cmGr. 14 
weight : 
83 kg –
charge 7.7 kg of Füllpulver 60/40 
length : 
502 mm
(without the fuze) 

fuze : 
Gr. Z. 04 or
Gr. Z. 04/14 

muzzle velocity : 
406 m/s 

max. range : 
8800 m with
the 8^{th} charge 

21cmGr. 14 A 
weight : 
83 kg –
charge 6.3 kg of Füllpulver 60/40 
length : 
500 mm
(without the fuze) 

fuze : 
Gr. Z. 04 or
Gr. Z. 04/14 

muzzle velocity : 
406 m/s 

max. range : 
8800 m with
the 8^{th} charge 

21cmGr. 17 
weight : 
120 kg –
charge 13.7 kg of Ammonal 
length : 
803 mm 

fuze : 
Kz.
Bod. Z. 10 

muzzle velocity : 
367 m/s 

max. range : 
9400 m with
the 9^{th} charge 8900 m with
the 8^{th} charge 8500 m with
the 7^{th} charge 

Elevation : 
+ 70° / + 6° 

Traversing angle : 
4° 

Wheels 
weight : 
254 kg 
height : 
1400 mm 

track : 
1610 mm 

Transport : 
drawn by
horses dismantled in two loads: barrel  4065 kg, carriage – 4455 kg 

Remarks : Quick firing
heavy mortar with hydropneumatic recoil system, wedge breech mechanism, boxtrail
gun carriage, and shield. Even before the beginning of the World War, the
standard wooden wheels were replaced by steel wheels
with pedrail of Rheinmetall construction. This
meant that the mortar could fire without a platform, making easier to move it
and faster to put it in firing position. It was adopted in
1910 and called simply Mörser without specifying
the calibre. At the beginning of WW1 German Army fielded 216 of these
mortars. The
Bulgarian Army received a little number of these mortars: the 1^{st}
battery of the 4^{th} heavy artillery was rearmed in 1918 with 2 – 21cm mortars, while the
16^{th} battery of the 3^{rd} heavy artillery regiment could
not receive its mortars due to the end of the war. 