2.75-inch Mountain gun M. 1911

 

 

 

 

British designation :

Ordnance BL 2.75-in. gun Mk. I on carriage mountain BL 2.75-in Mk. I

Bulgarian designation :

70-мм оръдие Армстронг

Calibre :

68.85mm L/27.8

Weight of the barrel :

187.8 kg

Weight in action :

586 kg

Barrel length :

1.940 m

Length of the bore :

1.840 m

Barrel grooves

number :

16

depth :

1.2 mm

Ammunition

 

Cartridge

length :

124.5 mm

diameter :

5.08 mm

charge :

212 g of cordite

H.E. Shell

weight :

5.67 kg – charge : 273 g

length :

245 mm

muzzle vel. :

393 m/s

max. range :

5304 m

Shrapnel

weight :

5.67 kg – 253 bullets x 11.1 g

length :

245 mm

fuze :

Time and Percussion Fuze No. 80 Mk V

muzzle vel. :

393 m/s

max. range :

5120 m

Elevation :

+ 22° / - 15°

Traversing angle :

8°

Recoil :

970 mm

Transport :

dismantled in 6 loads or drawn

Remarks :

Quick firing mountain gun using separate ammunition, hydro-spring recoil system, screw breech mechanism, traverse on axle. It was basically an improved version of the old 10 pdr mountain gun with a recoil system, a faster breech mechanism, a heavier shell and a shield. It was a screw gun design, where the barrel could be separated into two parts by means of a screw joint. Adopted in 1911, it entered in service in 1914. During the war 183 of these guns were manufactured, with 289,900 rounds.

The National Museum of Military History in Sofia exibits a 70mm Armstrong gun, a trophey probably captured to the British Army during the First World War.