Material Alloy steel. Weight (including breech mechanism) 1,248 kg.—2,745 lbs. Caliber 155-mm.—6.1 inch. Total length 2,332-mm.—91.8 inch. Length of bore 2,177-mm.—85.7 inch. Length of rifled portion of bore 737-mm.—68.4 inch. Rifling Number of grooves 48. Width of grooves 7.145-mm.—0.2813 inch. Depth of grooves 1-mm.—0.03937 inch. Width of lands 3-mm.—0.1181 inch. Twist, right hand, uniform, one turn in 25.586 cal. Powder chamber: Diameter 158.75-mm.—6.25 inch. Length 339.85-mm.—13.38 inch. Volume 6,965.75 cu. in.—425 cu. in. Obturation Pad. Firing mechanism Percussion. General Description. The 155-mm howitzer, Model of 1918 (Schneider) is of the hydro-pneumatic long recoil type, which may be used for direct fire, but was specially designed for siege fire. On account of its high trajectory it is able to direct shells on targets inaccessible to standard 6-inch howitzers of limited elevation. This howitzer has given satisfactory results in service and has proven to be more superior than guns of similar caliber. It has a muzzle velocity of 1,480 foot-seconds and attains a maximum range of 12,600 yards, the projectile weighing about 95 pounds. A maximum rate of fire of four or five rounds per minute may be attained, but heating as well as difficulty of preparing and transporting the ammunition by the gun crew renders such rate impossible for more than a few minutes. However, the normal rate of fire is two per minute and may be loaded at any degree of elevation. The howitzer is mounted on a sleigh and rigidly secured by means of a breech key and the holding down band. The sleigh contains the recoil and recuperator mechanisms which permits long recoil and insures stability at low elevations. When the gun is fired the sleigh recoils on bronze slides on the cradle, which is a U-shaped steel plate and rests in the trunnion bearings of the trail. This howitzer may be elevated from 0 degrees to 42 degrees by means of the elevating mechanism. The traverse is 52.2 mils right and left, the carriage sliding on the axle and pivoting on the spade, which prevents the carriage recoiling when the gun is fired. The customary shield protects the gunners from flying shrapnel and fragments. [Illustration: _155 M.M. HOWITZER MODEL OF 1918_ (_SCHNEIDER_)]