Bullets for varmint hunting are either flat-base or boattail and feature a tapered or spire point with the lead core exposed and swaged into a point. The jackets are thin, allowing these bullets to expand rapidly with an explosive force on woodchucks, prairie dogs and similar-sized, thin-skinned animals. This design also keeps these bullets from ricocheting when they strike the ground at velocities near 2000 fps. Because of their frangibility, varmint bullets are not suitable for large game.
Bullets for medium to large game require thicker jackets to keep them together while they penetrate deep into vital areas. They are designed for controlled expansion allowing the bullet to upset or “mushroom” as it goes deeper, making a larger hole which renders it far more lethal than a non-expanding type or a frangible one that breaks into fragments shortly after it strikes a body.
In medical terms, “lethality” is the effect of a particular bullet on a body. According to Dr. Martin Fackler — the leading wound ballistics expert in the country — bullet lethality is an easily understood concept. Lethality is determined by answering two questions: How big is the hole it produces? How deep is this hole? Bigger and deeper holes are more likely to intersect with vital organs, cause greater loss of blood, and result in death.
Game bullets are generally of a pointed-soft-point design — known as spitzer or semi-spitzer. These hold their velocity much better than less aerodynamic designs. Also available are large-hollow-point, flat-nose or round-nose designs with the lead core exposed. Attempts at improving expansion have been tried by varying the thickness of the jacket and by making cuts or skives in the jacket at the bullet nose to enable the jacket to split open and peel back in an even pattern as the core upsets. Other modifications are hollow points filled with hollow copper tubes, metal or nylon plugs which are driven back on impact, expanding the bullet.
Bullets for very large, dangerous game are subject to special requirements, since they often have to penetrate a considerable amount of muscle tissue and often heavy bone to reach a vital spot. Bullets for this type of hunting feature very thick jackets. Some like the old RWS and contemporary Nosler have two cores with a solid web of bronze running through the center of the bullet so that in section it looks like the letter “H”.
The top half expands, but only to the center web which insures that the base portion will stay together. Barnes Bullets offers what they call a “monolithic solid” which is simply a solid bronze bullet. Since these are made in large calibers such as 416 they are in effect pre-expanded. Speer offers a copper alloy bullet called “African Grand Slam” with a tungsten carbide dowel in the center for use on such extremely dangerous and hard-to-kill game as cape buffalo.