Introduction to Bullet Shapes
The diversity in bullet shapes and materials is a testament to the advancements in ammunition technology and the specificity of needs across different shooting applications. The bullet's design influences its trajectory, penetration, range, and overall ballistic performance. The correct bullet for a particular task depends on the intended application, whether for self-defense, hunting, or target shooting.
Full Metal Jacket (FMJ)
The FMJ bullet features a soft lead core encased in a harder metal shell, often made of copper or a copper alloy. This design minimizes barrel fouling and maintains a straight trajectory upon impact. FMJs are typically used in target shooting and military applications due to their cost-effectiveness and reliability. They feed well in semi-auto and fully automatic firearms and provide deep penetration, but tend to over-penetrate, posing risks in self-defense scenarios. The Hague Convention prohibits expanding ammunition in warfare, which is why FMJ is the standard military projectile.
Hollow Point (HP) and Jacketed Hollow Point (JHP)
HP bullets have a hollow tip intended to cause bullet expansion upon impact, creating a larger wound channel and transferring maximum energy to the target. JHP bullets are a variant of HPs but with a layer of tough material, usually copper, covering the lead core except for the hollow point. Both HP and JHP bullets are frequently used in self-defense and law enforcement due to their stopping power. They reduce the risk of over-penetration compared to FMJ. Some older firearms may struggle to feed JHP rounds reliably, and they cost more than FMJ.
Open Tip Match (OTM)
OTM bullets cater to precision shooting. The open tip is not designed for expansion but is a result of the manufacturing process -- it allows for more uniform weight distribution. These bullets offer superior accuracy over long ranges, maintaining a consistent flight path and an improved ballistic profile. They're favored by competitive shooters and military snipers (the Sierra MatchKing 175gr in .308 is a classic example).
Soft Point (SP)
SP bullets are intended for slower, more controlled expansion than HP bullets. The exposed soft lead tip deforms upon impact, facilitating deeper penetration and more energy transfer than FMJ bullets while still retaining good weight. This makes SP bullets popular in hunting scenarios -- they're widely used in rifles for deer, elk, and bear.
Frangible Bullets
Frangible bullets are engineered to disintegrate upon impact with hard surfaces, reducing over-penetration and ricochet risks. Made from a composite of powdered metals pressed together, they're ideal for close-quarters training and steel target shooting but have less range and precision compared to other bullet types. They're commonly used in police and military force-on-force drills and indoor training environments.
Boat Tail (BT)
BT bullets feature a tapered end that significantly enhances the ballistic coefficient. This design maintains velocity and resists wind drift over long distances, making them a preferred choice for long-range shooting and sniping. The boat tail design is often combined with other bullet types (e.g., Boat Tail Hollow Point, or BTHP).
Flat Nose (FN) and Round Nose (RN)
FN bullets have a flat point that makes them less aerodynamic but provides a hard-hitting punch on impact. They're commonly used in lever-action rifles because the flat tip prevents chain detonation in tubular magazines -- a pointed bullet tip resting against the primer of the cartridge in front of it could be catastrophic. RN bullets, with a rounded nose, have slightly better aerodynamics than FN bullets but are less stable in flight compared to pointed bullets. They remain popular in some revolver cartridges and older rifle designs.
Bullet Materials and Coatings
Bullets can be made from various materials, with lead being the most traditional due to its high density and malleability. Copper and copper-plated bullets are also common, especially in FMJ and JHP designs, where the copper jacket helps reduce lead fouling and increases structural integrity.
Lead bullets often require lubrication to prevent fouling. However, copper-plated and jacketed bullets usually don't need extra lubrication as the copper layer acts as a barrier between the lead core and the barrel.
In recent years, powder coating has been adopted as a technique to prevent lead fouling in the barrel. It involves applying a thin layer of dry powder to the bullet, which is then baked to create a smooth, hard finish. This is especially popular among handloaders working with cast lead bullets.
Conclusion
The science behind bullet design is intricate, revealing a delicate balance between penetration, accuracy, range, and impact energy. Knowledge about different bullet shapes, materials, and treatments can significantly enhance the shooter's effectiveness and overall shooting experience.
Want to learn more? Here's an excellent book on the topic:
If you know of any forums or sites that should be referenced on this listing, please let us know here.
