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Pressing Business

On the manufacture of extruded hexagonal Whitworth bullets

by George Arnold

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The operation is as follows:

The blank die (3) and the extrusion die (4) are fitted in the die holder (5). The extrusion die (4) has a 10° included angle lead to marry up to the blank die (3) which also has a lead for the punches (1) and (2). Ideally the die holder is then clamped under the ram using one of the punches fitted in the ram (6) for position. If there is not enough daylight the die holder can be used loose or on a swing arm, but at some risk of misalignment.

A lightly lubricated blank is then placed nose first in the blank die (3) and is pressed into the extrusion die (4) by the forming punch (1) which is made of steel. The 5/8 ø shoulder on the punch (1) prevents the punch entering the extrusion die (4). The forming punch (1) is then withdrawn, and replaced by the ejector punch (2) which is made of brass to avoid damage to the extrusion die. The ejector punch (2) pushes the blank (now bullet) out of the extrusion die (4). A bore mop may then be used to clean any lead flash from the dies. As the ejector punch is a round peg in a hexagon hole there will be some flash on the base of the bullet. The best way I have found to remove same is to roll the bullet base along about a 3" x ¼" sharpened plate as shown (7).

Select to enlargeThe pressure required to form the bullet is usually sufficient to form a base cavity. Pressure can be increased by using a longer or larger ø blank.

Yes, it worked, or I would be keeping quite! And for those interested, last time I looked the inch/metric exchange rate was unchanged at 25.4 mm to the inch.

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© 2006 G Arnold. First published in Black Powder Summer 2006, journal of the MLAGB
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