01 January 2013

Firearm Lethality: Pre Fragmented Bullets

12" penetration is the FBI recommended minimum
Different experts have different ideas about what makes an effectively lethal cartridge.  The FBI recommends 12 inches of penetration for a service pistol load.  I don't disagree with that.  What I do disagree with is that every single expert needs to explain that ALL bullets are deadly.  There is no smart/safe/magic bullet that only kills bad guys.  And no bullet technology makes up for safe gun handling skills.

A few posts ago we looked at Dr. Martin Fackler's pictures of military FMJ at various terminal velocities.  The fragmentation gained is largely a linear relationship with velocity.  To the right you will see a picture of some of the most common service pistol calibers with common Jacketed Hollow Point bullets.  They all do just fine in the penetration and expansion department.  Please note the ultra light, ultra fast 40 S&W load in the middle.

Since all bullets try to be accurate, we can assume that accuracy is NOT a competing factor between penetration and tissue disruption.  But as we have covered various designs as they have come out over the years, it becomes clear that penetration and tissue disruption are at odds with each other.  The monolithic non-expanding solids weigh the equation totally in the Penetration portion of lethality.  What if there were a bullet totally weighted towards tissue disruption? 

There are various makes on the market, and the most common names thrown out there are Glaser, Magsafe, and Dynamic Research Technologies.  Other companies are on the market, Extremeshock, RBCD, or Fastfire.  The biggest reason to use a pre-fragmented pistol round is to avoid "over penetration" and "ricochet" casualty causing events.  If your bullet started to break up the moment it hit anything solid or semi-solid, the smaller fragments would have less mass, and less mass loses speed quicker, which means less momentum to cause deep penetration which is a key factor in lethality.

Glaser was the brand that I first heard of, way back in the era of Windows 3.1 and 386 computers.  They were/are simply a plastic jacket filled with birdshot.  The use of glaser like ammunition in certain James Bond novels made them seem exotic and dangerous.  Of course I'm smarter now, and the glamor of phrases like "the compact fragments floating in their Teflon coatings impacted the gas tank, causing the unknown assailants car to explode" read better to a teenager who had no clue about 1) how hard it is to get a gas tank to explode, and 2) that pre-fragmented ammo won't reach the gas tank in the first place.

DRT 79gr 223 bullet, 10 feet from muzzle
Now, "pre-fragmented" ammunition is not a new idea.  The idea of cutting an X into the soft lead of a bullet to make discarding petals has been around since...well I don't know how long.

Magsafe bullets, lead shot in epoxy matrix
The question is, how do you keep all those fragments together while the bullet is spinning at several thousand rotations per minute?  So far there have been a three distinct answers.  Glaser uses a strong jacket that breaks apart on impact, DRT uses compression to sinter bond tungsten and other metal powders (Extremeshockusa uses a sintering process including a polymer), and Magsafe uses an epoxy glue to create a strong yet brittle medium to transport the lead shot.

Another type of ammunition that I will lump here, is multiple projectile bullets.  The US Government experimented with multiple projectile loads for the 30-06 to see if it would increase the hit probability for a rifleman (the project was abandoned, there is no substitution for marksmanship proficiency).  However Lehigh Defense still offers multiple projectile ammunition for personal defense.  This does nothing for ricochet concerns, but addresses the over penetration issue nicely. 
Lehigh 44 Mag multiple projectile

Each method works well enough for most purposes.  However, is there an increase in lethality with a pre-fragmented bullet over a normal bullet?  The answer is, it depends.  For a Central Nervous System (CNS) hit, the answer is "No" as any bullet will do, monolithic solid or DRT sinter core doesn't matter at that point.

So the lethality difference comes down to....shot placement.  If you shoot an attacker in the torso with a pre-fragmented ammo, and it fragments as advertised, you have a larger chance of getting something in some place where it ought not to be.  If you shoot the that attackers identical twin who is also attacking you with a hollow point bullet in the exact same spot, then we could answer this question with a stop watch as we waited for them to die.  Since I don't have those resources available, I'm going to say that bullet selection is not a replacement for shot placement, and anything worth shooting once is worth shooting twice.

Remember, all bullets are deadly.  It doesn't take too much to stop the cycle of life which is "fluid inside going round and round, air going in and out."  Such questions as "what kills faster" when talking about bullets is a poor question.  What people really want to know is, "if I screw up the shot, what bullet technology will make up for my shortcomings?"

The answer is, none of them.  Accuracy is still the number one most important part of lethality.  Penetrating in the wrong place and disrupting the wrong tissue doesn't give you immediate help in stopping an attacker, or charging animal. 

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