Bonded Core Bullets for Reloading
By Chuck Hawks
A bonded core bullet is one in which the lead core is soldered or chemically bonded to the copper alloy jacket. The purpose of bonding is to positively prevent core/jacket separation after impact.
The first bonded bullet that I can remember hearing about was the Bitterroot Bonded Bullet, long since extinct. Its core was soldered to its jacket and it had a good reputation for both weight retention and expansion. It was however, a very expensive bullet and not widely distributed, which probably accounts for its ultimate demise. Never the less, it was a bullet ahead of its time.
The idea remained and much later Swift introduced their successful A-Frame bullet. The A-Frame is basically a Nosler Partition type bullet with a pure copper jacket and a bonded core for greater weight retention and even deeper penetration than the original. This, too, is a very expensive bullet, but it is offered in a number of Remington Premium factory loads as well as to reloaders. The A-Frame is a flat base spitzer or semi-spitzer bullet without a lead point at the tip, visually similar to the Speer Mag-Tip and Grand Slam bullets. It has earned a very good reputation for use on large and dangerous game.
The Woodleigh Weldcore, made in Australia, is another bonded core premium bullet designed for use on large and dangerous game. It uses a soft nose design and a very heavy 90% copper, 10% zinc gilding metal jacket that is 1.6mm thick. This jacket is "welded" to the lead core, hence the bullet's name. The Weldcore has an excellent reputation in Africa for use on CXP3 and CXP4 game and is the bullet loaded in modern Kynoch factory loads. Federal loads Woodleigh bullets in their Cape-Shok .470 NE factory loads. The Weldcore is available to reloaders.
The Federal Trophy Bonded Bear Claw bullet is available in Federal factory loads and to reloaders under the Speer brand. (Federal and Speer are owned by the same parent company.) It uses a solid copper shank and a lead front core "fusion bonded" to the jacket for very high weight retention and deep penetration. It too has a flat base and a Mag-Tip type nose. Like the A-Frame, the Trophy Bonded bullet is recommended for use on large, tough animals.
Cor-Bon offers Bonded Core Soft Point (BCSP) and Bonded Core Hollow Point (BCHP) bullets in their Hunter ammunition line. These proprietary bullets are available in revolver and rifle calibers such as .357 Magnum, .44 Rem. Magnum and .444 Marlin. They are said to combine good expansion with very high weight retention and deep penetration. To the best of my knowledge, these bullets are not available to reloaders.
Two relatively recent bonded core bullets are the Remington Core-Lokt Ultra and the Federal Fusion. The Core-Lokt Ultra combines a 20% thicker overall Core-Lokt jacket with a 50% heavier inner belt and a true bonded core for increased weight retention and penetration compared to previous Remington bullets. This is a flat base, "Mag-Tip" style spitzer bullet. Remington claims that the Core-Lokt Ultra is the most accurate bonded bullet ever made. Core-Lokt Ultra bullets are available to reloaders in selected calibers and weights.
Fusion is a subsidiary of Federal Cartridge Company. This ammo line features a boat tail, "Mag-Tip" type bullet whose copper jacket has been "fused" to the lead core by an electro-chemical process. Their ad copy calls this, "a sophisticated and refined molecular application technique." (Apparently this means a plated jacket.) The jacket is of uniform thickness and the nose of the bullet is skived to promote initial expansion. This bullet's terminal performance is reputed to be similar to that of the plastic tipped bonded bullets. The Fusion bullet's performance has been specifically optimized for deer hunting. I do not believe that the Federal Fusion bullets are available to reloaders.
Swift followed up on the success of the A-Frame with the Sirocco, the first plastic tipped bullet to feature a bonded core for superior weight retention (and thus penetration) compared to standard tipped bullets like the Nosler Ballistic Tip and Hornady SST. This bullet uses a tapered jacket that is thin at the tip and much thicker at the base. Such a jacket is designed to allow the front of the bullet to open quickly but to retain an adequate shank that, along with the extra weight retained by the bonded core, assures decent penetration. The Sirocco also has a boat tail and a very high ballistic coefficient (BC) for a flat trajectory down range.
The Sirocco was a commercial success and eventually Nosler and Hornady responded with bonded core versions of their Ballistic Tip and SST bullets. The Nosler version is the AccuBond and Hornady's bonded bullet is the InterBond. Nosler also produces a black Lubalox coated "Combined Technologies" version of the AccuBond for Winchester as the AccuBond CT. All of these are plastic tipped, boat tail bullets of high BC, all have tapered jackets and all are available to handloaders as well as in factory loads. They are more expensive than standard bullets, but not outrageously so. These are the bonded core bullets that are probably of greatest interest to most reloaders.
The plastic tipped bonded bullets are different from the A-Frame, Weldcore, and Trophy Bonded bullets in that they are designed primarily for use as all-around bullets, rather than specifically for large game. (The same can be said of the Remington Core-Lokt Ultra.) These are bullets designed to expand readily for reasonably fast kills on CXP2 game like deer and yet retain enough weight to assure adequate penetration in CXP3 game like elk.
The fast expansion is due to the plastic tip and moderate forward jacket thickness, while the deeper penetration (relative to standard plastic tipped bullets) is due to the greater weight retention provided by the bonded core feature and the heavier part of the tapered jacket. Like the older (non-bonded core) Nosler Partition bullet, these new plastic tipped bonded bullets are an attempt to provide the best of both worlds.
These plastic tipped, bonded core bullets do not usually fragment inside the vitals of deer size game and therefore may not kill as quickly as standard soft point, hollow point, or tipped bullets known for rapid expansion. The whole point of the bonded core is to retain weight for increased penetration and these bullets are alleged to retain about 60-90% of their original weight.
They do expand reasonably well against moderate resistance and are generally more humane for use on CXP2 game than the very tough, deep penetration bullets that are likely to simply punch a relatively small hole clear through a deer, expending most of their energy on the landscape beyond.
This represents a real advantage for the reloader who feels compelled to use a premium bullet on CXP2 game. Most of the previous bonded core bullets, like the A-frame, Weldcore and Fail Safe, are designed primarily for use on CXP3 and CXP4 game. Such bullets will kill deer, to be sure, but they usually will not give the quick "four feet in the air" type of kill often provided by standard soft point and plastic tipped bullets.
On the other hand, the plastic tipped bonded core bullets usually do not penetrate to the depth of a Fail Safe, A-Frame, or Weldcore in very large animals. I would not recommend them for use on CXP4 game, for instance. However, as a "jack of all trades" among bullets, they are hard to beat. Their blend of high ballistic coefficient, adequate expansion and superior penetration makes them one of the best choices for all-around use and mixed bag (CXP2 and CXP3 game) hunts.
Note: Additional information about bullets can be found on the AMMUNITION, BULLETS AND BALLISTICS section of the Rifle Information Page.
Copyright 2005, 2012 by Chuck Hawks. All rights reserved.