War Department Notes - Barrels Pattern/53

G.C. Holden, Assistant Superintendent of Stores

Boring

The barrel is then passed to the boring room where it is first strengthened by hammering on the outside.

It is then bored for the 1st time with a 3 grooved bit or "Auger bit", turned at a slow speed. This brings up the diameter of the bore to .56 of an inch. The object being merely to take off the scale, this is called "Rough boring". It is then bored for the 2nd time this is done with a 4 square bit with 4 sharp edges.

An oak* spill is inserted between the bit & the barrel on one side to keep the barrel steady. It is turned at a quick speed and brings the bore up to .565 in diameter.

The barrel is afterwards bored for a 3rd time - and this is done also with a 4 square bit with only 2 sharp edges and the 2 others blunt - the reason of the blunt ones being to burnish the barrel as the boring moves. A deal spill is inserted on one side next to the blunt edges-this turns at a slower speed & brings up the diameter of the bore to .572 inch.

* The reason the oak spill is here used is in consequence of the high speed which deal would not stand.

After each boring the barrel is straightened by the eye with the aid of hammering, and is called Shading and is done in this way.

There is a black board fastened along the top of a window. The barrel is rolled in the direction of the board, or until the line of the board is brought in line with the interior of the barrel so as to throw a shade down the barrel. Now if the shadow comes down straight it will show that the barrel is straight. Reverse the barrel and get the shade down from the other end. If there is any dent or bulge in the barrel the edges of the shade will be broken at the spot where the inequality occurs.

The outside of the barrel can be shaded in the same way holding the barrel at such an angle as to get the shade thrown on the outside of the barrel.

This is the only certain mode of ascertaining the straightness of a barrel & requires much experience in its execution.

In shading a rifled barrel you must get the shade down the lands.

Milling the Barrel

The barrel is milled at both ends which brings it to the length of 39.125 inches.

Countersinking Breech

This consists in enlarging the bore at the breech end to receive the Breech Screw or Pin. The barrel is then turned externally and afterwards ground on the outside and in grinding a steel mandrel is passed down the barrel and fitting it exactly prevents the grinding stone injuring it. Grinding has the effect of showing up any little imperfections which there may be in the metal - such as "Greys" or seams.

After the grinding it goes thro' a mending process, which is to be done with a hammer and chisel closing up the seams or knocking out the "greys" if they are very slight, but if the imperfections which are shown up by the grinding are too bad to be mended the barrel will be condemned.

The breech and lump are now milled for the first time to take off the superfluous metal.

Seat for Front Sight

The seat for the front side is cut out by hammer and chisel in the form of a dovetail, and the end of the barrel being heated the sight is brazed on by borax and brass clippings, the former being used as a flux.

Tapping the Breech

The breech of the barrel is tapped to receive the breech screw or pin.

This is done by different taps, of which there are four altogether - each tap making the thread a little deeper, except the last, which is intended merely to burnish or smooth the edges of the screw.

Screwing in the Breech piece*

The breech screw, pin or piece, is next turned in & set to position ready for milling.

* The breech pin is the only part of the barrel which cannot be made interchangeable. Every barrel is obliged to have its own and after it is screwed they are both numbered with the same number and a mark is put across the bottom of the breech and on the tang of the breech pin, the object being to show when the breech pin is properly screwed up. The reason it can't be made interchangeable is that the thread of the screw cannot be made to begin exactly at the same spot.

Milling

At this stage of manufacture of the barrel there is a series of millings of the front sight, breech, lump etc to extending over 17 operations to bring these parts up to proper form.

Polishing

The outside of the barrel is polished with emery and oil.

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