A TUBE FOR A 12-INCH GUN JUST OUT OF THE FURNACE, WHERE IT WAS TEMPERED AT WHITE HEAT AND IS NOW READY FOR QUENCHING IN THE PLANT OF THE MIDVALE STEEL CO.
The gun tube is 41 feet long.
TUBE OF A 155-MILLIMETER GUN BEING TURNED, PRIOR TO BORING, AT THE TACONY ORDNANCE CORPORATION PLANT.
TUBE OF A 155-MILLIMETER GUN IN A LATHE BEING BORED.
The ingot out of which this tube was made, came from the mold in an octagonal shape and later was forged into a square shape and finally made round. It now, too, has the hole bored partially into it. Through this hole, ultimately, will pass the projectile.
The forging press used for the larger caliber guns, such as 14-inch and 16-inch, is of a 9,000-ton weight capacity.
After the ingot forging has been reduced from squareness to a cylindrical shape under the press, it is allowed to cool, then taken to the machine shop, where it is turned and the hole through which the projectile ultimately will pass is bored into it. This hole is somewhat smaller than the diameter of the projectile, because in the finishing operation, when the gun is assembled finally and put together, the hole must be within one-one-thousandth of an inch of the diameter required, which is all the tolerance that is allowed from the accuracy to which the projectiles are brought. Otherwise the accuracy of the gun in firing would be injured and the reliability of its aim would not be satisfactory.