Profiling – The Effects of Rifle Bullet Shape

Am Shooting Journal ^ | 3/17/20 | P Massaro

[w1n1]

Tailor ammunition choice to Hunting area, Species, Shot distances to Maximize Best Options - Not all bullet profiles perform the same, and you should choose the profile that best suits your hunting scenario. Looking at ammunition advertisements, or while reading articles on hunting or shooting, you will invariably come across terms that are used to describe the shape and/or profile of a bullet. Ballistic coefficient, sectional density, boat tail, secant ogive, flatnose, roundnose, hollowpoint; the list goes on and on.

Which design is best for your shooting or hunting needs? Looking back through the history of the projectile, the earliest jacketed bullets were roundnose designs, hearkening back to the lead bullet designs of the mid- to late 19th century.
At moderate ranges, these bullets offered everything a hunter or shooter needed: plenty of accuracy, a weight forward design that aided in straight line penetration, and a compact length to-width ratio that didn’t take up all sorts of room in the case. Near the turn of the 20th century, and especially due to the battlefield results of the Spanish-American War, the U.S. Army decided to revamp its choice of the .30-40 Krag, and settled on the .30-03, retaining the 220-grain round nose bullet of the Krag.
It would be only three years until the U.S. would follow the lead of European designers, modifying the ’03 case and utilizing a lighter, pointed spitzer bullet. A boat tail – almost as crucial as that pointed nose – helped to increase the aerodynamic properties of the bullet at longer ranges, allowing for a flatter trajectory and for better retained velocities as distances increased.

In fact, the boat tail showed up on the scene as early as 1901, to give you an idea as to how rapidly the science of ballistics was evolving. Fast forward to 2020, and you’ll see all of the above designs still on the market, and still doing well, each for its own reason. Let’s take a look at the benefits and downsides of the different rifle bullet designs to help aid you in your decision-making process.

THE ROUNDNOSE BULLETS – so popular among the classic cartridges and those who enjoy using them – can still make an effective choice for the hunter, providing the distances at which you intend to take game aren’t too great. For the intents of this article, I’ll include the flatnose bullets in this group as well, as they’ll perform much the same.

The major issue with roundnose bullets is that their ballistic coefficient
– the measure of how easily they will slip through the atmosphere
– tends to be low, and their velocities will drop off after 200 yards or so.
If you’re hunting inside of that number, and I’m certain that for most of us in the eastern part of the country this is true, these bullets pose no real handicap, as more than likely you are shooting a big game cartridge powerful enough to be zeroed at 200 yards.

MOVING TO THE spitzer design, you will see a definite advantage in trajectory when the shots get longer. Classic designs like the Nosler Partition, the Sierra ProHunter, many of the Hornady InterLocks and SSTs, the Barnes TSX, and others represent what I refer to as a middle-of-the-road choice for hunters, as you will see the trajectory flatten out past 200 yards, and the amount of retained energy increase at longer distances. Read the rest of effects of types of bullets.

[youngidiot]

What’s this got to do with corana?

[IndispensableDestiny]

My hunting loads in .308 Winchester use 165 gr Nosler Ballistic Tip (green tip) or Accubond (white tip). If I think I’ll be shooting close in (less than 100 yards) I’ll go with the Accubond. Anything else, the Ballistic Tip. Both bullets fly the same with the same load (from my rifle).

[eastexsteve]

The article says:

The long-range precision shooters – those who ring steel out past 1,000 yards and sometimes out past a mile – rely on this bullet profile for all of their work, as no other bullet design will give the reward at long ranges that the boat tail spitzer will.

Actually, when the distance is 600 yards or greater, the conversation is based upon what is the best boat tail spitzer to use. Not all perform the same. The .30 caliber Sierra Match King 168 grain BTHP spitzer has for years been the gold standard for .308 Winchester long range shooting. However, as that bullet starts to slow down approaching subsonic speeds, (usually at beyond 700 yards for many .308 guns) they tend to start flying erratically. Most shooters blame this on the 9 degree angle at the tail of the bullet. However, it's slightly heavier brother, the 175 grain BTHP has a 13 degree tail angle and seems to be much more stable when approaching the transonic barrier.

In my opinion though, the king of long range bullets for .308 Winchester is the 185 grain BTHP Berger Juggernaut. I shoot this bullet at distances greater than 1500 meters with good accuracy.

[WinMod70]

My round of choice for many years was 180 gr Remington bronze points in 30-06. They started to become hard to get and then my buddy that did my reloading passed away. I about 5 years ago I switched to factory Federal Premium Accubonds and got my son using Federal Premium 140 gr ballistic tips in 7MM-08. They are quite devastating on whitetail.

[WinMod70]

My round of choice for many years was 180 gr Remington bronze points in 30-06. They started to become hard to get and then my buddy that did my reloading passed away. I about 5 years ago I switched to factory Federal Premium Accubonds and got my son using Federal Premium 140 gr ballistic tips in 7MM-08. They are quite devastating on whitetail.

[Vaduz]

No meat in store deer and rabbit hunting ensues.

[Manly Warrior]

All bullets loose quite a bit of accuracy as they slow into the transonic velocity range. mach2.3 to .9 ish, the center of pressure moves forward and yaw of repose, the angle of the axis of the bullet compared to the line of travel, increases and air resistance goes up great ly, slowing and destabilizing it further, boat tail design mitigates this somewhat, with 11-13 degrees being about the ideal, often, bullets literally suddenly tumble out of stability and basically fall to the ground.

Any bullet looses accuracy as it slows into transonic, so high bc/drag coeff bullets at highest velocity reasonable makes for extended range. The venerable 308 is about the minimal cartridge in 30 Cal for much past 1000, and that with heavy bc bullets an long barrels. Bump up another 200+ fps at the muzzle and range steps up a notch too.
Even better these days, is a heavy 6.5 or7mm in a medium large case like the 260/6.5 class, or a bit larger, increases effective range well past the decidedly slow 308 and a185+ bullet. Golly, if one can handle the recoil, a 30/06 and a 200-240 class bullet easily hold above transonic out to around 1500, with legs that can take it to early 2000 before it too, stumbles well into the low transonic, sub Sonic range and accuracy falls off.

Long range target folks seldom use 30s, most use 6.5s, for all the above reasons, plus much lower recoil based shooter effects.

Mil stuff still hangs with the 30, as terminal ballistics matter against other than paper or just ringing a gong.

I still abuse a 308 in my Palma gun as it is required, but my barrel is 32 inches and 1/13 twist, since 155s are the only bullet allowed. 155 @3150 stays above 1900 past 1000, but brass is once and done.

[MileHi]

Thanks. This post made clicking on the cheesy blog thread worth it.

[Harmless Teddy Bear]

Men, like bullets, go fastest and furthest when they are smoothest.

[Manly Warrior]

Welcome. The article actually is pretty good, discussing bullet shape and construction in general.

BTW, Mach 1.3, not 2.3, I guess I fat fingered the number. around 1350- to 1050 fps, dependent on atmospherics is transonic.

Staying above 1350 is best for overall accuracy, but really slippery and well spun ( stability factor, Sg, well above 4 or so) bullets can make it through this danger zone and come out subsonic and stable for really long range. accuracy. They just are trudging along like a pistol round at that point, so caliber and mass matter for downrange effects.