Flat Base Or Boatail How and Why: the Bullet Does the Actual Killing. The

Flat Base or Boatail how and why: The bullet does the actual killing. The rifle is simply a means to deliver the bullet to the target. So, a basic knowledge of bullets seemed to be a prerequisite for studying rifles. As hunters, we put a lot of thought into the tips of our bullets. Roundnoses, spire points, plastic tips and such are all worried over to ensure that the bullet we’re using is right for the game we’re hunting. But have you ever given as much consideration to the other end of your bullet–the base? In the scheme of things, the base of your bullet probably isn’t going to make any more of a difference between a hit or a miss, a clean kill or a wound, than the bullet tip, but it is something to consider if you’re on a once-in–a-lifetime hunt and want to eliminate as many variables as possible that could leave you standing there wondering what went wrong if a trophy animal bounds away seemingly unscathed. There are generally two types of bases on hunting bullets, flat base and boattail. The practical differences between them may not be what you think. Both have their benefits, and their drawbacks. For example, when it comes to pure accuracy, flat base bullets are inherently more accurate than boattails, and that’s why you see the “short range” Benchrest shooters using them. The reason is because it’s easier to make their bases perfectly square with the sides of the bullets than it is to make boattails perfectly concentric and on straight. Another benefit of flat base bullets is that for a given caliber and bullet weight, they’re shorter overall, so are more easily stabilized in a slower rifling twist. That shorter length, however, puts their center of gravity more toward the rear of the bullet, and that tends to offset stability gained from the shorter length. Finally, flat base bullets generally experience less jacket to core separation on impact. If you think of the bullet jacket like an ice cube tray and the lead core as the ice, it should be obvious that the right angle inside of a flat base jacket holds onto the core better than the tapered inside of a boattail jacket. On big game, you want a bullet that penetrates, and that means using a bullet that stays together and retains its weight instead of coming completely apart during expansion. I’m not suggesting standard cup and core boattails is the wrong bullet to use for hunting. They have their place and their advantages, such as at very long range on light-bodied game. Boattails increase the ballistic coefficient of bullets, which helps them overcome air resistance and wind deflection. The difference in the amount of bullet drop between flat base and boattail bullets won’t amount to much until well past the range of 400+ yards, but the boattail’s better ballistic coefficient makes errors in wind deflection correction and range estimation more forgiving. Whatever loss of accuracy there is from the boattail’s inherent manufacturing flaws are more than offset by their ability to overcome adverse or unknown shooting conditions. And if you’re a handloader, boattail bullets are simply easier to start into a case mouth and seat with less chance of crumpling or bulging the case neck. Thankfully, bullet technology is at a point where we really don’t have to choose between a flat base and a boattail for good terminal performance. There are plenty of bullets that give you the benefits of both without some of their drawbacks. From a design standpoint, Nosler has its Solid Base boattails that retain their cores during penetration better than standard cup-and-core boattails. With the Solid Base design, the entire boattail base is solid copper, so instead of being tapered inside the base, the lead core bottoms out against a flat surface. It’s like Nosler made a flat base inside a boattail so there’s less a chance of the core popping out as it impacts and passes through game. That design also shifts the bullet’s center of gravity forward helping with stability. There are also bullets that mechanically retain the core such as Hornady’s InterLock boattail bullets. An InterLock is essentially a raised edge inside the bullet jacket that grips the core solidly when it’s swaged into place during bullet forming. I’ve shot a lot of big game with Hornady InterLock bullets and I can’t recall an instance of jacket/core separation. Another technique to help boattail bullets perform better is by bonding the jacket and the core. Often, this bond is so strong that it’s not uncommon to recover expanded bullets with significant amounts of lead still bonded to the petals instead of being ripped or wiped off. Swift Bullets uses bonding in its Scirocco II line, and if you section one you’ll also see that the lead core sits in a flat-bottom cavity much like Nosler’s Solid Base bullets. Of course, we can’t forget all-copper bullets such as Barnes. They offer the sleek design and high ballistic coefficient of boattail bullets, and expand reliably without any lead core at all. The of Benchrest and military specialists demanded bullet makers to make boattail bullets that behave like flat bases at all ranges, and flat base bullets that behave like boattails at long range. Those efforts include rebated boattail designs that have an abruptly reduced bullet diameter before the boattail is formed, and FBVLD, or flat based very low drag bullets that have an extremely long nose, or ogive, for minimum nose drag to compensate for the greater base drag. Berger Bullets has their VLD’s too. They use a method of forming boattails so that they are more concentric in conjunction with hybrid ogive’s used. Well I guess since I have gotten this ball started I may as well keep it rolling. Bullet Shapes & Characteristics In addition to the variations of expanding bullets that we have already covered, there are five different general shapes of hunting bullets: flat point, round nose, semi-spitzer (semi-pointed), spitzer (pointed), and boattail spitzer (pointed with a tapered heel). Flat point and round nose bullets have a blunt nose, the difference being merely whether it is flat or rounded. Typically, this allows a lot of lead to be exposed at the nose of the bullet, which makes for reliable expansion, especially at lower velocities. These designs also tend to penetrate in a reasonably straight line, and are reputed to be less apt to be deflected off course by intervening leaves, twigs and brush that they might encounter on their way to the target. As a consequence of their blunt nose, RN and FP bullets exhibit greater air drag, lose velocity more rapidly, and therefore exhibit a more curved trajectory. Spitzer and semi-spitzer bullets have a pointed nose and a flat base. Spitzer bullets are sharply pointed, minimize air drag, and therefore shoot "flatter" than bullets with a blunt nose. But, spitzers have a tendency to tumble on impact if they don't expand, and don't initiate expansion as reliably as flat point or round nose bullets. The most streamlined hunting bullets are boat-tail spitzer bullets. These have a pointed front-end and a tapered heel (amazingly like the stern of a sailboat). Boat-tail spitzers exhibit the least air drag and shoot flatter than the other shapes. Compared to spitzer bullets, the advantage of the boat tail is most pronounced after the bullet has fallen below the speed of sound. So the boat tail spitzer is a good design for very long range shooting, say in excess of 300 yards. Their terminal performance is similar to other spitzer bullets, but they have a reputation for more readily losing their cores. Frangible Bullets Frangible bullets break up into very small pieces upon impact with the target or the background. The penetration of this type of bullet is limited and the inflicted damage is typically near the surface of the target. They are the safest type of bullet to use in semi-populated areas, as the risk of ricochet is minimized. Frangible bullets are normally used to take animals weighing less than approximately 30 pounds (These small animals are typically called "varmints.") by creating significant damage within the first few inches of the impact point. The frangible bullets that are typically used to hunt varmints are called "varmint bullets." Well DAH! Because controlled expansion bullets and non-expanding bullets are more strongly constructed, they may simply pass through a small animal causing less than immediately lethal damage; the animal will painfully suffer as it heals or slowly dies. A humane hunter wishes neither, so frangible bullets are the ticket for hunting small animals. Non-Expanding Bullets Non-expanding (FMJ) bullets typically retain their general shape as the bullet penetrates and passes through target. The penetration of this type of bullet is usually much greater than frangible or expanding bullets because the frontal area of a non-expanding bullet does not increase as it penetrates. Since the wound channel is typically much narrower than that of an expanding bullet, the damage caused by a non-expanding bullet is usually much less, and quick kills on deer size game are rare. For this reason non-expanding FMJ bullets are illegal for big game hunting almost everywhere in North America. In round nose form they are favored by some African hunters for use on the largest and toughest game, principally on elephant and rhino, where very deep penetration against heavy hide and bone is required.

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