NEW AUSTRIAN 6-IN. BRONZE-STEEL GUN. 
419 
In No. 2 gun tlie rifled portion is 1*2 calibres longer than in No. 1, 
as the grooves are extended for that length into the shot-chamber, 
starting from the cone where this chamber—which is (2 mm ) 0*078 ins. 
larger than the bore—joins the powder-chamber of still larger dia¬ 
meter. ( Vide figure below.) 
The object of this extension of the rifling is to centre the projectile 
as soon as it begins to move. 
In both guns the vent is of copper in two pieces, and strikes the 
powder-chamber at light angles at (75 mm ) 2*95 ins. from the face of 
the breech-block. 
The B.L. apparatus is exactly similar to that of the field guns of 
1875,* the breech-block being of bronze-steel and the obturator of 
copper. The plate at the end of the paper shows approximately the 
gun in question j though, as many of the required data are wanting, 
its dimensions are not in all cases correct. 
The projectiles for the gun with uniform twist were furnished with 
four copper rings—two towards the front and two towards the rear; 
while the shell for the gun with increasing twist had only two rings— 
one towards the front to ensure centring, and one towards the rear for 
rotating the projectile. 
The normal charge was to be that which would give a muzzle 
velocity of (450 ms ) 1476 f.s. to a shell of 85*5 lbs., with a maximum 
pressure of (2000 k ) 13*1 tons per square inch in the powder-chamber. 
Experiments were begun in 1877, several natures of powder being 
tried:— 
Size of grains. Density. 
^•1 .. . 
1*721 to 1*772 
1*671,1*686, 1*702 
That adopted was No. 3, of density 1*686. 
No. 2 
C (6 mm ) I 
..... £ 0 , 25 £ ... 
No 3 ( (12 to 15 mm ) l 
1N0 * d .t 0*47 to 0*60 j 
* Vide “Proceedings, R.A. Institution,” Vol. X., No. 1, p. 5. 
