416 
NEW AUSTRIAN 6-IN. BRONZE-STEEL GUN. 
12*94 lbs. By these improvements the muzzle velocity was increased 
by 263 f.s. 
This addition to the charge, however, gave a pressure upon the base 
of the projectile, on leaving the bore, of about 3*5 tons, which was 
thought to be too high. A new gun of cast-iron, 10 calibres longer, 
was therefore made, being a B.L. gun with the Krupp breech-block 
and Broadwell ring. In June and July, 1867, a muzzle velocity of 
1411 f.s. was obtained from this gun, the shell weighing 73Jlbs., and 
the charge of powder (pebble, 0*4 to 0*6 in. in diameter) 16*2 lbs. At 
a distance of 415 yds. its projectiles could penetrate plates of about 
5*2 ins. The errors in range and direction were, however, considerable, 
being due apparently to the effect of the high velocity upon the lead 
coating, which was much torn, overriding the grooves. 
In 1868 experiments were made in Prussia with a steel 15 cm B.L. 
gun (made out of a solid block and not ringed) furnished with the 
double wedge B.L. apparatus of Kreiner. Principal data as below :— 
Weight 
of gun. 
Calibre. 
Total 
length 
(about). 
Length 
of bore 
(about.) 
Twist. 
Powder 
charge. 
Weight 
of chilled 
iron 
shell. 
M.V. 
cwt. 
ins. 
ins. 
ins. 
lbs. 
lbs. 
f.s. 
60 
6-0 
108 
90 
1 in 63 
15-4 
76 
1345 
The results were good, the gun penetrating, with the chilled iron 
“ Griison 99 shell, plates of steel of 6*98 ins. thickness at a distance of 
164 yds. The accuracy of the piece was, however, insufficient, and the 
gun considered too weak for the charges used. 
It was determined, therefore, to increase the weight of the gun, to 
strengthen it with rings, to lengthen the rifled portion from 14 to 
18 calibres, and to furnish it with a Krupp cylindro-prismatic B.L. block 
with Broadwell ring*. 
Messrs. Krupp were charged with the carrying out of these improve¬ 
ments, both for naval, garrison, and siege guns; but as the accuracy 
of fire' still proved insufficient, the Prussian authorities decided upon 
another pattern with a sharper twist. 
43 of these latter guns were ordered from Krupp by the Austrian 
Marine, and in 1872 one of them was tried at Pola. The data as to 
these guns will be found at page opposite. 
Meanwhile, experiments were continued in Austria with the long 
(15 cm ) 6-in. cast-iron gun, and were completed early in 1873, showing, 
according to the Report of the Committee— 
1st. That the accuracy of the cast-iron long 15 cm gun was satis¬ 
factory, and much superior to that of the 15 cm gun of model 1861. 
2nd. That an envelope of hard lead offered no advantages. 
3rd. That the twist adopted suited very well for muzzle velocities 
of from 1493 f.s. to 1575 f.s. 
4th. That the copper rings employed weakened the projectile and 
injuriously affected the accuracy of fire. 
