31 December 2012

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 to win wars or market firearms for sporting purposes.  The 8x57, 7x57, 30-06, 6.5x55 are all common sporting calibers to this day, and yet the Lebel is not.

Different formulas for bullet jackets have come and gone, the industry standard in western culture 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.  Soft steel is still largely used by the ComBloc industries, mainly for cost savings purposes over gilding metal.  The ComBloc ammunition industry also has a fondness for steel cartridge cases for the same cost savings benefit.  We will leave the ComBloc ammunition behind for the rest of this discussion as FMJ bullets behave the same in tissue (unless they fragment due to velocity on impact).

7x57 loads by Kynoch, far left representative of the original 173gr load
The first truly "modern" military cartridge that saw widespread international adoption was the old 7x57 Mauser (modern in the sense of being a bottlenecked rimless cartridge design).  This is because it was adopted by so many military forces across the planet and by many sportsmen in Europe and America (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.  A historical side note, two Colt M1895 machine guns in 7x57 were used by Roosevelt's Rough Riders, and it was the performance of the Mauser design and 7x57 cartridge in the Spanish American war that directly led to the abandonment of the Krag rifle and 30-40 cartridge and the adoption of the 1903 Springfield and 30-03 cartridge (which would be reworked to 30-06 three years later).

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.  It should be noted that the 9.3x62 Mauser cartridge is capable of launching a 286gr projectile at 2,350 fps.  This velocity seemed to be the right mix for early nitrocellulose based propellents and available bullet technologies to make reliable animal stoppers for hunting in Africa. 

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 as the first imitator of the Lebel Ball D in 1905.  Countries around the world followed suit; America in 1906, Russia in 1908, Great Britain in 1910, and Spain in 1913.  FMJ bullets are the norm by the time WWI comes around.  Italy wouldn't adopt a spitzer bullet until the 7.35x51 Carcano round between the wars, and Sweden holding on until the last minute before WWII.  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 in 318 Westley Richards, 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 (something that Col Charles Askins would discover again with his 8mm-06 wildcats pushing 150gr bullets over 3000fps).  This causes a lot of wounds clost to impact, but poor immediate lethality.  The advertisements for the "250-3000" included such phrases as, "I'm thankful for 3000 feet per second!" when referrencing encounters with bears, unfortunately the 86 grain bullet developed a reputation as a "wounder" as it did not hold together sufficiently when impacting at high velocities at short range.

There are two answers to this. The first answer is:  Use heavier traditional bullets at a reduced 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.  Since the velocity craze has not gone away (and velocity is nice when you are trying to buck wind), the current market for extra tough bullets able to handle impacts on tissue at high velocity is better than ever and still expanding.

So there you have it, smokeless powder and new cartridge designs combined with better bullets gave rise to the velocity craze (300 Weatherby Magnum came about in 1944, Nosler Bullets started their business in 1948, so the premium bullet segment lagged behind the velocity department by a little bit).  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 (easily over 2,500 fps now without any issues of peak chamber pressure).  Although the continued success of the 30-30 Win and resurgence of 45-70 Government cartridge indicate there is a still a part of our shooting community perfectly happy with heavy bullets at moderate velocities to harvest game cleanly.

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.

8 comments:

Badger said...

Well done, both parts & nicely illustrated. Your use of Fackler's chart should remind people the importance of what the bullet is doing "out there" at the other end of its flight. I've found heavy-for-caliber bullets (in terms of current marketing thought) tend to shoot & perform better.

Anecdotally, a conversation with Nosler awhile back revealed they felt they had to also strengthen up the composition of their 120gr 7mm Ballistic Tip because velociphiles were loading it up in their blasters anyway. That result made it a good penetration candidate in something more modest such as a 7mm-08 where it continues to hold together well while creating a monster wound channel. But that's an anecdotal exception (personally experienced) & I still believe that you stated the case for a robust projectile at somewhat modest velocity well. One has to look at the whole picture.

Nicely done.

libertyandlead said...

The 7x57 (and the 7mm08) is a wonderful all around hunting cartridge and took everything before the magnum craze took over. I probably wouldn't choose it over the .308 today, but it has a warm place in my heart.

Great article, looking forward to more. -55six

Colorado Pete said...

The .303 Brit round using a 215 soft point round nose at roughly 2200 fps was a great killer in Africa and India too, for the same reasons. Heavy for caliber (high sectional density), moderate velocity producing moderate expansion, and deep straight penetration with the bullet generally holding together well.

Nathaniel Fitch said...

I found a few errors in the post, and I also had a few comments on it.

You say that the French "failed dismally to use the 8mm Lebel" (para.). In what way did they fail to use the 8mm Lebel? This is a fairly aggressive charge for such an introductory article.

Gilding metal is not the most common jacket material. Steel is, though it doesn't see much use in the US. This is a minor quibble, I admit.

In what way is the 7mm Mauser "the first modern rifle cartridge" that the 8mm Lebel or 7.5x53mm Swede are not?

It is strange to hear you say that "when you got what you got, you go for accuracy and penetration". Accuracy and penetration were and still are prioritized by military requirements. Regardless of the limitations of powder technology, accuracy and penetration will always be high priorities for military cartridges.

The Germans did not invent the spitzer bullet. The French did, with the Balle D of 1898. The German S Patrone followed a full seven years afterward.

How did Roy Weatherby ignite "velocity fever"? He is sometimes credited with proliferating it, but interest in very high velocity (3,000 ft/s+) cartridges absolutely predates him, going well back to the .250-3000 Savage of 1915. It is strange to talk about Weatherby, who mostly influenced the American hunter, when discussing a subject that mostly seems to be concerned with military full metal jacket loads.

Anyway, I hope you can stand my constructive criticism. The article had some sections I very much liked, such as the paragraphs on OTMs and bullet construction.

AM said...

Nathaniel Fitch,

This article was focused on small arms development mainly of sporting cartridges for the purpose of taking game or self defense (how bullets interact with tissue), although there is definite crossover across the history of firearms between military and sporting/civilian cartridges.

Steel FMJ bullets are not very "interesting" in the sense that they all pretty much act the same, and steel jacketed bullets are not used for sport hunting I've ever met or read about. They kill the same as anything else, but are specifically banned from hunting in the United States (exceptions for varmints or non-game species like pig).

In terms of lethality, bullets that are designed to both expand and penetrate deeply are "interesting" to me. Bullets that are designed to hold together (steel jacketed FMJ) are less interesting.

The 250-3000 used a light 86gr or lighter bullet to achieve that velocity, but quickly earned a reputation as a "wounder" as the cup and core bullets of the time would not hold together, a problem that Weatherby reloaders would encounter, which caused the rise of bullets designed specifically for higher velocities as mentioned. So Savage backed off the velocity hype. Roy Weatherby was a helluva salesman and the "velocity craze" he started definitely sold firearms. Meanwhile gunwriters like Jack O'Connor are singing praises to the high velocity of the 270 Winchester.

So when I say "velocity craze" I mean as an advertising blitz to sell guns. Not that magnum cartridges don't have their place, just that a 300 Hyperunobtanium magnum won't kill a deer deader than a 30-30 will, but you'll find salesmen who assure you that to make that 500 yard shot across an open canyon, you need the Magnum. In reality the ballistics don't support the hype, but the hype sure sells guns.

I actually had a Major tell me that a 308 might be good for a 400 yard shot. I smiled, nodded politely, and didn't mention that I have no problems shooting to 600 with my AR using iron sights.

I hope this answers your questions, if not please let me know.

AM said...

Sorry, I forgot to clarify "the French dismally failed to use it" is directed at the utter failure to achieve any sort market dominance based on being the first.

The Germans on the other hand, would sell anything to anyone. Which is why you see M98 rifles still being manufactured, 8x57 ammunition still on the surplus market from time to time (drying up very quickly though). The Lebel never made the jump from a military cartridge to a sporting cartridge.

AM said...

Anyone visiting from the "World of Tanks" forum, a response to "BabyOlifant" has been published here: http://randomthoughtsandguns.blogspot.com/2014/02/addressing-criticism.html

Nathaniel Fitch said...

AM,

Thank you for taking the time to address my comment. I have sent you an email and would rather continue discussion there.