Part One: Bullet Basics

As I've been spending more time in the forums I have become somewhat curious about the bullet choices people are making out there. This series is intended as a primer to get people up to speed on what they're seeing in the marketplace, a brief history on where these innovations came from and what purposes they serve, if any, in the field. More importantly, it just may help you cut through all the hype and hyperbole and make the right choice(s) the first time.

I don't want to bore you, so this bit of background will be brief. Feel free to skip this section if you're already studied in it, if not it will help you to understand how we got to where we are at and what to look for / expect going forward. To this, I'll just gloss over some fundamental concepts and historical data and focus only on the concepts required for a working understanding of where the modern bullet originated and how it developed into those sleek, flat-flying projectiles commonly launched today.

Not long after you started walking, you probably discovered for yourself that the very best throwing rocks were the smooth, round ones. They don’t have as many irregularities for the air to to ‘catch’ and influence their flight, they fly straight and true. Not long after that, many of us experimented with the slingshot, metal bearings are usually the ammo-of-choice here due to their density. As it turns out, the heaviest common metal is lead, so once we started using chemistry (gunpowder) to throw rocks (balls), lead got the nod.

Sometime before the American Revolutionary War, bright young gunmakers discovered that spinning the lead balls in flight made them fly straighter, so they fashioned spiral grooves into the bore called "rifling." The next major breakthrough came as a French army officer Claude-Etienne Minié invented the bullet that would bear his name in 1849. The Minié bullet, a cylindrical lead bullet with a hollow base that expanded when fired, worked with even more devastating effect for two primary reasons - the expanding base sealed the bore tightly and evenly, plus its more streamlined cylindrical shape cut through the air better so it travels farther, faster and more accurately.

The next breakthrough we are concerned with here is the jacketed bullet. Simply stated, once velocities hit a certain point (e.g. the advent of smokeless power) it was soon discovered that the soft lead stripped past the rifling, so a wrapper, or guilding metal, was required around the lead to retain a bite on the grooves and keep the lead core more stable on impact.

Fun Fact  - Gilding metal is a copper alloy, a brass, comprising 95% copper and 5% zinc. British Army Dress Regulations define gilding metal as '8 parts copper to 1 of zinc'.

It was with all this newfound velocity that things got tricky. When lead started crashing into stuff at a few-thousand f.p.s., it of course tended to shatter because it was so soft and a bullet that shatters will no longer penetrate. So jackets got thicker and thicker, and bullets got heavier (for caliber) and heavier so they'd perform adequately. (Some even got the full metal jacket treatment, when no expansion was desired.)

Fun Fact  - Round-nose bullets stabilize at a lower r.p.m. than sharp bullets of the same weight and diameter, the twist rates can be slower. That's why many heavy-for-caliber pills are round-nosed - so they stabilize in the standard twist barrels. In fact the .30/40 Krag, as well as the immediate predecessor of the .30 Govt. 1906, the .30-03, fired 220 grain round-nosed pills. The key 1906 upgrade was the improvement to the lighter, pointed, 150 grain spitzer bullets common today.

Many other important observations were made during this progression, as you'd expect, but that's essentially the short version of how we got here. Literally all of the improvements since that .30 caliber, 1906 round have been performance enhancements of the same fundamental features found on bullets to this day. To better understand them, lets take a quick look at what a modern bullet looks like.Sectioned Modern Bullets

  1. Point (Tip)
  2. Meplat
  3. Ogive
  4. Cannelure
  5. Shank (Bearing surface)
  6. Heel
  7. Base (Flat)
  8. Boattail Base
  9. Core (Lead alloy)
  10. Jacket

Why is all of this vital to know? Because changing the size, shape, position or material composition of each of these critical features not only changes how your bullet flies, but also how it reacts terminally when striking our anticipated target. If you don't know how each of these features of a bullet can affect your day you will be relying on little more than trial and error to achieve your desired results, as you will see in Part Two.

Here's a brief synopsis of how each feature can effect performance.

  1. Point - We are all aware that pointed bullets shoot "flatter" but did you know the size and composition of the tip can also effect expansion?
  2. Meplat - One of the more important features if you are concerned with terminal performance (expansion), the wider the meplat the faster it will expand, all else being equal.
  3. Ogive - The curved portion from the shank that terminates at the point. This is where a great deal of the research is being done to improve long-range ballistics. Longer, more gentile ogives are more streamlined and retain velocity better, but are inherently less-stable than shorter pills and therefore require a faster spin.
  4. Cannelure - The rolled, serrated ring around the middle of the bullet has but one useful purpose - to crimp the mouth of the case into to hold the bullet. It does nothing else of consequence and should be avoided unless necessary.
  5. Shank - That parallel portion of the bullet that engages the rifling. The length of said engagement is called the bearing surface. Longer bearing surfaces raise internal pressures due to friction - short bearing surfaces may not orient or stabilize the bullet well, so a balance must be struck.
  6. Heel - The concentricity and uniformity of this corner at the base of the bullet is critical to accuracy. Irregularities, nicks or dents, even leaving case mouth burrs when bullet seating, may allow hot powder gas to escape differently on one point than another at the instant of release from the muzzle, causing a flyer. In a coattail bullet, this critical function is moved forward to the shoulder of the 'tail and the shank where it is more protected and easier to control during manufacture - this could explain at least part of the reason they have a reputation for accuracy.
  7. Base - The south end of a north-bound bullet.
  8. Boattail - tapered portion at the rear of the bullet, usually thought to improve long-range aerodynamic performance as well as consistency (see "heel").
  9. Core - The dense internal section of a bullet, usually made of an alloy of lead and antimony. (Pure lead is usually too soft). The hardness of the alloy is critical to terminal performance - too soft it blows-up, too hard it shatters.
  10. Jacket - The guilding metal (copper-zinc) envelope that encloses the core. Jackets are often tapered and / or scored (drawn thinner at the front) to at first encourage, then thicken at the base to slow the expansion rate of the bullet. Cores are sometimes bonded to jackets, and jackets with solid base, partitions and other internal structures are often used with varying affect on terminal performance as well (more later).

There, we've gone from The Origin Of Man to the late-20th century in just a few paragraphs! Relatively painless, was it not? Now that we're all on the same page, we can go on to the really fun stuff and keep it all straight...