Firearm Lethality: Part Two: copper and lead.

By the end of the 1800's the French had taken the lead in military technology with the 8mm Lebel cartridge.  It contained a brass case, a primer, smokeless powder, and a full metal jacketed spitzer bullet.  The lack of commercial 8mm Lebel ammunition on the market today is no reflection on the actual design of the cartridge, in power it is sufficient, and other than being a rimmed cartridge (something that seems quaint today, despite our perennial fondness for the 30-30 Win) there is nothing inherently wrong about it, save for the dismal failures of the French in actually using it.

Different formulas for bullet jackets have come and gone, the industry standard is "gilding metal" which is 95% copper, 5% zinc, which makes it actually a brass alloy.  Different allows, cupronickel, tin, even steel have all been tried with various levels of success.

7x57 loads by Kynoch, far left representative of the original 173gr load

The first truly "modern" military cartridge that saw widespread adoption was the old 7x57 Mauser.  This is because it was adopted by so many military forces across the planet, and by many sportsmen in Europe (to include the British who renamed it the 275 Rigby.  From elephant to dik dik the 7x57 took game all over Africa, and made quite a good showing of it.  The original military loading of the 7x57 was quite sedate by modern terms, a 173 grain full metal jacket bullet at 2,400 fps.

Note this number, 2,400 fps, it comes up a lot.  The 416 Rigby, a "Safari" stopping cartridge used a 400 grain bullet at 2,400 fps.  The 375 Holland and Holland used a 300gr bullet at 2,400 fps.

So, you are asking, since we have smokeless powder, modern primers, brass, and firearms, why the sedate velocity?   That is a very good question.  The first answer is that not all smokeless powder is created equal.  The British Cordite propellant and other nations smokeless propellents were not mixed with burn controllers or coated with burn regulators.  So in terms of ballistics, you "got what you got" from a propellant and had to make the most of it.  And if you have to make the most of it, go for Accuracy and Penetration.  So the heavy for caliber bullets at moderate velocities continued to dominate.  Even the 30-30 Winchester is famous for using heavy bullets for the powder charge given.

6.5 Carcano wound profile, similar FMJ RN wound profile for 7x57 173gr FMJ RN loading or 6.5 Mannlicher, or original 6.5x55 military load.  Note the deep, straight penetration.

But all of that is background data to explain jacketed bullets.  Ballisticians discovered that the spitzer bullet flew better than round nose bullets.  And Germany once again lead the way, with the adoption of a spitzer bullet for the 8x57 (.323 bore) JS.  Countries around the world followed suit, and FMJ bullets are the norm.  The FMJ spitzer with a boat tail or flat base carries momentum well, has a relatively high Ballistic Coefficient, and wounds adequately.  In tissue the long nose and squat base of the bullet cause the bullet to "flip around" in tissue or ballistics gelatin in order to achieve the most stable manner of movement, putting the center of mass forward.  The only difference between a 22 caliber bullet and a 30 caliber bullet is how quickly that transition takes place.

FMJ bullets are a "cup and core" bullet. The jacket is drawn first, then the core is inserted, lastly the jacket is rolled over the base of the core to keep it locked in place.  This rolling over the base of the bullet is why FMJBT bullets are not used for competition by serious competitors.  The Open Tip Match (OTM) or Hollow Point Boat Tail (HPBT) is a reverse drawn jacket, meaning that the core is put in from the front, and then the jacket is smoothed down to form the nose ogive.  This puts the "folding" errors of the final step much closer to the center of rotation (increasing stability) and gives the match bullets a much more uniform base.

Traditional soft nose hunting bullets, flat base or boat tail, are built the same way as the competition bullets, save that the lead is exposed in order to provide expansion.  Various methods of keeping the jacket together with the core to provide stability to the core have been done over the years, from metalic bonding to locking rings.  Some premium bullets abandon the tradition drawn jacket and core method, such as the Partition, which puts a solid gilding metal divider between the front core and the back core.

6.5mm Berger 140gr hunting VLD.  Total separation on a deer shot from a 6.5x284  Photo by BigShooter of californiapredatorsclub.com

So why have I gone into methods to keep the core and the jacket together?  Remember that magic number? 2,400 fps?  This is the "magic velocity" where the traditional cup and core bullets will hold together, expand reliably, and give good penetration and weight retention.  Above this velocity the jacket starts to separate and weight is lost, below this velocity the lead doesn't expand much.  For what it is worth, the magic velocity to make normal FMJ bullets fragment reliably is around 2,500 fps and higher.

Courtesy Dr. Martin Fackler

Now you can put it all together as to why Bell was shooting elephants with a sedate 7x57.  The FMJ load was heavy, giving good sectional density and very little deformation to ensure excellent penetration, and the velocity was adequate to get the bullet where it needed to be.  On a different note, after switching to a heavier rifle, Bell commented that some of his "inexplicable misses" suddenly went away.

However, let us go away from the first quarter of the 20th century.  Roy Weatherby has succeeded in igniting velocity fever, and normal bullets aren't getting more lethal, in fact they are going so fast that when they hit they open up completely before penetrating deeply.  This causes a lot of wounds, but poor immediate lethality.

There are two answers to this. The first answer is:  Use heavier bullets at a reduce velocity.  Shooting a 150gr bullet at 3,400 fps into ballistics gel will show you that it won't penetrate nearly as well as a 220gr bullet at 2,800 fps.  Mass gives momentum, and momentum allows for penetration.

The second answer is; Use tougher bullets.  Bonded core (where the lead is basically soldered to the gilding metal jacket), partitioned bullets like the venerable Nosler Partition already mentioned, or the Swift A-Frame pictured, use a bullet with a thicker jacket, or use bullets with locking rings, a thicker portion of the jacket that circles tighter around the core to keep it in place.

So there you have it, smokeless powder combined with better bullets gave rise to the velocity craze.  It should be noted that powder improvements have allowed even sedate old standby rounds to get a new lease on ballistic life.  The 375 Holland and Holland can be loaded a bit faster than 2,400 fps with a 300 gr bullet now that it is not dependent on cordite.

I have not gotten into monolithic bullets here, or bullets where the gilding metal is used as the expansion portion of the bullet.  Nor have I covered other metals added to bullets to increase armor piercing attributes.  That however, will be another post.

On the pistol front, there was no velocity revolution to cause any sort of new designs to come out requiring metal jackets.  Metal jacketed pistol bullets are generally around simply to allow shooters to not have to deal with barrel leading, and Hague treaty compliance for military forces (in FMJ form).  All other traditional jacketed type of bullets are simply gilding metal clad variations of their pure lead counterpart.  More exotic types of handgun projectiles will be covered later.