Heel-type bullets have a reduced base portion that fits inside the cartridge case. The most common example of this is the 22 rimfire. Early blackpowder cartridges used the heel-type bullet, also, so that the bullet diameter was the same as the case diameter, and fit the barrel with the full section of the bullet that was "outside" of the cartridge.
|There are three ways to make a heel type bullet.
|The difference in diameter between the heel and the shank of the bullet is normally the same as the case thickness, which can be .012 to .020 inches. The greater this difference, the easier it is to use a hollow faced punch (since the thickness of the steel walls on the cylinder need to be reasonably strong). Tiny differences are best handled with the dual diameter die, rather than a punch. Generally it is best to pre-form the exact core weight and shape in a core swage die, and then form the bullet in a second die, because this eliminates the need to try to develop extrusion pressure at the same time that the heel is being formed. The pressure needed to form the heel properly may be higher than required to extrude lead through the die bleed holes, resulting in partly formed bases. Using a separate core swage solves this problem.
The bullet base itself, beyond the "heel" or undersized portion, can be flat, hollow, cupped, or conical as shown here. These changes are simple to make and are created by the geometry of the heel base punch in reverse. A conical cavity in the punch creates the pyramid shaped base shown. A hollow base design allows the base to expand from gas pressure, and assists in allowing a slightly over-sized heel to fit easily into the cartridge. However, hollow bases can be problematic in regard to crushing, unless at least .030 or more inches of wall is left. Conical and boattail shaped bases may tend to reduce drag and can be most effective on sub-sonic rounds.
|Here are the tools for heel base bullets:
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