Bullet design and function

Paul Miller explores whether your projectiles are doing excess damage to small game

The subject of bullet construction and what is the right projectile to use for different purposes is one on which many books have been written. Let’s look at the basics of what a bullet is and how they differ in their formation and performance.

The word ‘bullet’ is derived from the French word ‘boulette’ which roughly translated into English means ‘little ball’. The earliest muzzleloading rifles fired a round lead ball that was wrapped in a loose cotton patch and then rammed down against the previously loaded charge of powder.

The barrels were originally smooth bore like a shotgun but with time rifling was invented when it became recognised that stabilising a projectile by making it spin improved its execution. Shooting with muzzleloading rifles is still popular worldwide and is a great connection with the history of our sport.

With the advent of the metallic cartridge and the single-shot breech-loading rifle, the world opened up to the design of shapely lead cast bullets. Varying their shape occurred as a better understanding of ballistics developed. It was soon discovered that a bullet with a pointed profile was more efficient than one with a round nose. This happened in 1832 in England with Army Captain John Norton’s design of a conical bullet.

It was followed closely by English gunsmith William Greener honing a bullet with a wooden plug in its base which expanded on firing and forced the slug to fit the rifling.

Moving on, in 1847 the soft lead Minie ball was perfected by French Army Captain Claude-Etienne Minie. It was conical in shape with a hollow cavity in the rear which had a small iron cap installed in the base rather than a wooden plug. On firing, this cap also pushed forward in the cavity of the bullet and forced the projectile to expand and contact the rifling. In 1855, the British adopted the Minie ball into their Enfield rifles.

The next important change in bullet design and construction occurred in 1882 when Director of the Swiss Army Laboratory, Lt Colonel Eduard Rubin devised the copper jacketed bullet. This pellet was elongated and featured a lead core in a copper jacket. It was a profoundly important progression because lead bullets were historically only able to be fired at lower velocities. This was because the surface of the lead bullet, in contact with the hot gases of the powder burn at the rear and with the rifling on its way down the barrel, would melt at higher velocities. The advantage of a copper jacket was that copper is harder and has a higher melting point, so bullets constructed in this way were now able to be fired at greater velocities.

So to summarise, bullets for muzzleloading firearms were round and mostly moulded from pure lead. This worked well because they were fired at velocities less than about 1450fps. Then later, moulded bullets manufactured with a combination of lead and tin fired well in more modern firearms with rifling in their barrels at slightly higher velocities. Copper jacketed bullets with a lead core were developed and are the most commonly used worldwide because of their ability to withstand much higher velocities and be designed and constructed for different purposes.

Today we have a large number of manufacturers producing an incredible array of highly sophisticated bullets designed specifically for every conceivable use from military to target, and of course, hunting. When you consider the evolution of the bullet and then you see how relatively quickly this transpired in recent history it is quite mind-boggling.

We can now choose bullets that are lightly constructed and therefore explosive when driven at high velocity for small game shooting. The same can be said for larger game in Australia like feral pigs. Here we can choose a more stoutly constructed bullet that holds together better for penetration through a mud encrusted hide and then mercifully kills the animal by wrecking its lungs or heart.

When we move further up the scale to larger deer or all the way through to buffaloes in the Top End, heavier and even more stoutly constructed bullets become appropriate. For the biggest of game animals, solid or monolith construction bullets are employed to transfer energy and retain their weight to push through to the vitals and again ensure a merciful despatch. That is what every ethical hunter should always aim for when choosing their bullets for their particular cartridge and game animal.

Stepping back to small game we have copper jacketed bullets that can be driven at speeds in excess of 4000fps and still hold together in cartridges like the 17 Remington, .220 Swift, .204 Ruger and .22-250 Remington. If a small game hunter wants to shoot foxes for their skins then bullet construction in combination with velocity becomes important. Foxes are lightly built animals and not difficult to kill. The issue is more the preservation of their skin.

A great deal of work has gone into developing projectiles by manufacturers like Nosler, Hornady and Sierra that are copper jacketed but with thin jackets and fine hollow-points or plastic ballistic-style tips. This is to enhance aerodynamic qualities and increase explosiveness when the bullet hits a fox or other small fur-bearing animal.

Ideally the bullet fragments completely then stay inside the animal. It is an expanded bullet exiting that causes the damage to fox pelts. Alternatively, shooters can use a solid or more stoutly constructed bullet at lower velocity that passes through the fox with minimal exit damage. The problem here is knowing where that solid bullet ends up after it exits the fox and whether it does a good job of killing it humanely because it expands so little on the way through.

If you are shooting rabbits for the pot you really need to head shoot them, otherwise they will be completely ruined by the highly frangible projectiles in these hyper velocity smaller bore cartridges. The alternative of course is to use a smaller rimfire cartridge with a hollow-point or plastic-tipped projectile at a distance where you can be sure of head shooting them as well.

Bullet design is now so sophisticated that manufacturers can vary the thickness of the bullet jacket and the shape of the bullet as well as the internal structure of the lead core. This makes the bullet explosive or hold together for penetration and achieve the mushroom effect that bigger game hunters look for to shift energy to the animal and create a greater wound channel to aid in a caring kill.

There has always been the argument as to whether a bullet should be designed to mushroom but still pass through a big game animal to generate a blood trail for tracking or whether the bullet should mushroom sufficiently to remain inside the animal. The latter imparts all energy to the animal rather than only part of the energy with the rest spent on the bullet exiting and travelling off downrange. I favour the ‘stay in the animal’ camp and using up all the energy on a humane despatch, but the debate will continue to fuel ever more sophisticated bullet designs to potentially achieve the best of both worlds.

How do you choose the perfect bullet for your purposes? You look at what the manufacturers recommend on their factory boxes of ammunition. You talk to your reputable gun dealer. You ask your experienced mates. You buy a quality manual like the Nosler or Hornady reloading guides. These are essential if you plan to reload but are also hugely useful for learning about bullet construction and the ballistics of various bullet shapes and construction. For the shooting enthusiast these high-quality books provide a wealth of information to allow you to choose the right projectiles and powder combinations to achieve exactly what you want in terms of bullet speed and results on target.

The internet is a huge resource with Wikipedia, Google Search, YouTube and various shooting forums helpful with questions and answers about what bullets you should you use for different purposes.

Taking the time to do this research is really enjoyable and will make you more knowledgeable and successful at the range or in the field. There is also no substitute for being out there, having a go and learning from your experiences at the range or with hunting both small and larger game. As if we need an excuse to do more shooting! Good luck.

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