March 10, 2020
By Joseph von Benedikt
What's the difference between bonded and non-bonded bullets and why is that important? Because bonding is one of the most advanced, authentic ways of controlling bullet performance. Even by not using the bonding process, manufacturers choose certain terminal performance characteristics. By understanding the advantages and disadvantages of bonded bullets, you'll be better prepared to choose a bullet suitable for your hunting applications.
Bonding By the Book
To begin with, let's examine just what bonding is. On the surface, it's simple: It's the process of molecularly securing a bullet's lead core to its jacket. However, the various methods used to accomplish this are anything but simple. Some bullet makers use what is basically a soldering process, wherein the lead core is melted inside a copper jacket until lead fills the available space and adheres to the copper. Others use an electrochemical process, wherein the jacket is more or less applied to the outer surface as plating. Still others are bonded via undisclosed proprietary processes.
So, what's the purpose of bonding? In short, it prevents the jacket and core from separating on impact. Bullets that hold together tend to retain weight better, which translates into deeper wound channels. Bonded bullets particularly perform better when heavy bone is encountered. Deep penetration and integrity through bone and very dense muscle is a very real advantage on heavy, thick-skinned big game such as moose, bison and, to a lesser extent, elk and many African plains game animals.
Non-bonded bullets, on the other hand, have their own advantages. They are much less expensive to manufacture, so they are less expensive to purchase. They are also less complex to manufacture, which theoretically should offer an accuracy advantage: with less steps in the process, there are fewer opportunities for variables.
On a performance note, non-bonded bullets typically expand violently on impact and wreak devastating internal havoc, resulting in very fast kills on light-bodied, thin-skinned game such as deer and antelope. They often perform beautifully on bigger, heavier game too, when shot placement is behind rather than through the shoulder. However, non-bonded bullets are much less forgiving for use on heavy big game: Less-than-ideal shot angles often result in insufficient penetration.
Let's examine the predicted terminal effects of bonded vs. non-bonded bullets during common hunting scenarios:
For example, a mature bull elk can weigh close to 1,000 pounds, as compared to a mature whitetail, which rarely exceeds 250 pounds. A non-bonded bullet that will drive through the shoulder of a quartering-too whitetail and destroy the vitals will likely fragment in the dense shoulder muscle and against the heavy bone of the elk, and while portions of it will probably get into the vital cavity, they'll likely reach only one lung. Big, hardy ungulates with one good lung can cover miles in their attempt to escape, making for a very long, arduous recovery effort.
It's important to note that bullet fragmentation is much more likely when fired at very high velocity. Standard-velocity cartridges such as the .308 Winchester, .30-06 Springfield, 7mm-08 Remington, and so forth perform very well with non-bonded bullets and can achieve impressive penetration when stoked with a good bonded bullet. Magnum cartridges that push projectiles at 3,000 feet per second (fps) or more from the muzzle are typically better served with a bonded bullet, even on deer-size game.
Broadside Behind the Shoulder
When a hunting bullet impacts a broadside game animal in the crease behind the shoulder and slips between ribs: Depending on nose design, the tip of the bullet mashes rearward, forcing the soft lead core behind it to expand, bulge outward and flow out and rearward, creating a mushroom shape. If velocity isn't excessive and bone isn't encountered, most bullets will retain that mushroom shape and push on through, shedding fragments to the sides, until it either exits the far side of the animal or slows and halts (which often occurs against the hide, which - supple and resilient - catches many bullets with a trampoline-like effect).
As they pass through, non-bonded bullets tend to mushroom bigger and shed more fragments, resulting in something of a scrambled egg effect on the vitals. When bullets lose considerable weight, mass and momentum are compromised, often resulting in penetration isn't particularly deep. Pass-through results - where the projectile exits the animal - aren't uncommon on deer and antelope-size game but are rare on bigger animals.
Bonded bullets, depending on design, tend to mushroom in a more controlled fashion, retain more weight and penetrate deeper. Pass-through results are typical on deer-size game and not uncommon on elk.
Broadside on the Shoulder
Now let's consider a broadside impact on the shoulder. The nose of the bullet reacts similarly, but more dramatically since muscle is denser than vital organs. The bullet may or may not encounter a shoulder bone or rib, but let's assume it does. While smashing through the bone, both types of bullet will lose considerable weight and become distorted; a non-bonded bullet may actually fragment into smaller chunks. Neither will likely retain the classic mushroom shape but will be expanded into a big, gnarly chunk of jagged lead and copper plowing through the vitals. Forward progress will be diminished by the impact with bone, but the bonded bullet will retain far more weight. On a big, heavy animal such as elk, the bonded bullet is more likely to make it all the way through the vitals before halting, and often, it will still exit.
Some non-bonded bullets feature design characteristics that maximize integrity on impact, such as the locking ring in the bullet jacket on Remington's Core-Lokt and Hornady's InterLock; the "H" jacket design of Nosler's Partition, and so forth. (As an aside, the Partition was the first hunting bullet specifically designed for weight retention and deep penetration, and to this day, it gives the best of the modern, bonded bullets a run for their money.) While a mechanical core-to-jacket lock isn't as effective as bonding, it does offer enhanced integrity. Remington's Core-Lokt has become one of America's most trusted bullets.
As always, when choosing a bullet for heavy game, always go with a heavy-for-caliber version, whether it's bonded or not. For instance, you're better off with a 180-grain .30-caliber bullet for use on elk than with a 150-grain version.
Bonded & Non-Bonded Bullet Roundup
Following is a list of popular bonded and non-bonded lead-core hunting bullets, along with subjective performance comments. Keep in mind that while bonded bullets are typically the best bet for use in fast magnums, many of the non-bonded bullets are just fine for use in more pedestrian cartridges.
Classic cup-and-lead-core hunting bullet with exposed lead tip. Good performance on deer-size game. Flat base, lead tip.
Known for forgiving accuracy, this bullet is a classic lead-tipped projectile well suited for use on deer-size game. Both flat and boat tail designs, lead tip.
Known for dramatic, violent expansion, maximizing shock on deer-size game but minimizing penetration. Good aerodynamics courtesy of a boat tail and polymer tip. This bullet was recovered from an Oryx.
Nosler Ballistic Tip
Accurate and devastating on deer and antelope, and good for elk in heavy weights fired from standard-velocity cartridges. Excellent aerodynamics courtesy of a boat tail and polymer tip.
An "H" shaped jacket with separate front and rear cores, the Partition offers dramatic expansion that produces tremendous shock coupled with the deep-penetrating characteristics of a protected rear half that can't separate. The bullet of choice for magnum cartridges before bonded bullets became available. Flat base, lead tip. The bullet on the left center was recovered from ballistic gelatin at 400 yards, while the bullet on the right was recovered from gel at 50 yards.
Arguably the non-bonded bullet by which all others are measured. Known for beautiful mushrooms and outstanding performance, it's ideal for deer and elk-size game when fired from standard-velocity cartridges. Flat base, lead tip.
Sierra Pro Hunter
Flat-base bullet with lead tip, known for forgiving accuracy and outstanding performance on deer-size game. This particular bullet was recovered from an elk.
Boat-tail bullet with lead tip, very accurate, offers similar performance on game to the Pro Hunter but has better aerodynamics.
Winchester Deer Season XP
Winchester addressed the needs of deer hunters with Extreme Point bullets in their Deer Season XP load. The projectiles have a polymer tip with a larger impact diameter, offering rapid expansion that translates to larger wound cavities for faster kills.
Federal Trophy Bonded Tip
Of boat-tailed, polymer-tipped design, this projectile has a solid copper shank rear of center. The front half of the bullet has a bonded lead core. Accurate and one of the best deep-penetrating bullets available. The bullet on the left center was recovered from ballistic gelatin at 400 yards, while the bullet on the right was recovered from gel at 50 yards.
This inexpensive boat-tailed, lead-tipped bullet is electrochemically plated and is gaining a reputation for accuracy and terminal performance out of its price league.
Known for accuracy, boat-tailed, polymer-tipped bullet is one of the softest of the bonded projectiles, making it ideal for use on all game from standard-velocity cartridges. The bullet on the left center was recovered from ballistic gelatin at 400 yards, while the bullet on the right was recovered from gel at 50 yards.
Winchester Power Max Bonded
This bonded hollow point bullet has a contoured jacket that features high weight retention with significant expansion. Available in most major centerfire rifle cartridges, the Winchester Power Max Bonded is a great choice for taking medium to large-size game.
Probably the most popular of all bonded-bullet designs, the boat-tailed, polymer-tipped AccuBond is known for accuracy and exceptional terminal performance. Also available in a high-BC version specifically designed for long-range hunting. The bullet on the left center was recovered from ballistic gelatin at 400 yards, while the bullet on the right was recovered from gel at 50 yards.