US Army Technical Manual 9-463 -Gun, 8 in ., Mk . VI, Mod.3A2 and Mount, Railway, Gun, 8 in ., MIA1, 1942

US Army Technical Manual 9-463 -Gun, 8 in ., Mk . VI, Mod.3A2 and Mount, Railway, Gun, 8 in ., MIA1, 1942

1 . SCOPE. -a. This manual is published for the information and
guidance of the using arms and services and ordnance maintenance
personnel.
b . In addition to the description of the 8-in. railway gun materiel,
this manual contains technical information required for identification, use
and care of the materiel .
c. Complete disassembly, assembly, inspection, maintenance and
repair instructions are included in the manual and are for the information
of ordnance personnel .
2. DATA.- a. Weights, dimensions, and ballistics of the 8-in. -gun,
Mk . V1, Mod. 3A2.
Depth of rifling . . . . . . . . . . . . . . . . . . . .07 in .
Length of bore . . . . . . . . . . . . . . . . . . . . 45 calibers
Length of rifling . . . . . . . . . . . . . . . . . . . 288 .79 in.
. Type of breechblock . . . . . . . . . . . . . . . . Interrupted screw
Type of firing mechanism . . . . .. . . . . . . Electrical and percussion
Type of rifling . . . . . . . . . . . . . . . . . . . . Right hand, uniform twist,
one turn in 25 calibers
Weight of gun with breech mechanism . 42,000 lb .
b . Ammunition Data.
Maximum range . . . . . . . . . . . . . . . . . . 32,000 yards (approx .)
Maximum service powder pressure . . .38,000 lb . per sq . i n .
Muzzle energy (A .P. 260 lb. shell) . . . . 13,647 ft . long tons
Muzzle velocity
A .P. 260 lb . Mk . XX (Normal charge) . 2100 ft . per sec .
(Super charge) . . 2750 ft . per sec.
H .E . 240 lb . M103 (Normal charge) . .2150 ft . per sec .
(Super charge) . . . 2840 ft. per sec .
Practice projectile 260 lb.
(Normal charge) . . . . . . . . . . . . . . 2104 ft. per sec .
(Super charge) . . . . . . . . . . . . . . . 2750 ft. per sec .
Seating of shell
A.P . 260 lb . . . . . . . . . . . . . . . . . . . . . 74 .75 in .
H .E. 240 lb . . . . . . . . . . . . . . . . . . . . . 70 .5 in .
Travel of projectile in barrel
A .P . 260 lb. . . . . . . . . . . . . . . . . . . . . 294 .6 in .
H .E . 240 lb . . . . . . . . . . . . . . . . . . . . . 298 .59 in .
Volume of powder chamber . . . . . . . . . 5,410 cu . in .