The Wall Speaks

 

I was seated in the classroom at a shooting school, listening to the experts.  The topic?  We discussed the pros and cons of 100-yard zero, point-blank range, twist rate, and other AR-15 related topics.

Almost every serious discussion of firearms will eventually flip to home self-defense.  That session was no different.  The AR-style gun has a lot to recommend it.  https://tactical-talk.blogspot.com/2023/12/the-ar-at-home.html

The problem is over penetration.  While most rifle students present were thinking of hits, I couldn't help but wonder about misses.  Do enough training and you'll realize misses are the problem.

The instructor proposed a solution for us.  "Don't worry about overpenetration.  You don't need expensive frangible rounds; use plastic-tipped varmint rounds.  Those things just explode in small animals.  What do you think will happen if they hit something hard?"  This made sense.  It's even mentioned it in the above link.

I've heard a lot of urban tall tales about .223 bullets.  I remember hearing that .223 Remington bullets were inherently unstable and would disintegrate in a body before sufficient penetration  We haven't seen that.    You can find tons of YouTube videos of shooting at ballistic gel.  Here's one: https://www.youtube.com/watch?v=8HM96wpPVoQ

Or, how this bullet was prone to tumbling in flight, making it impractical for competition shooting.  Or, how it will shoot your lungs out!  Oh, wait, that was 9mm.

There is only one way to tell.  Go shoot through a wall of your house and see what happens.  It was a great idea, so I did that.

I took a sheet of half-inch plasterboard out of my bedroom, which was undergoing remodeling, and made a small wall section with 2x4 studs.  I also added a three-quarter-inch thick Styrofoam insulation board and a small sheet of quarter-inch wood paneling. 

The wall and target

Should the bullet leave the wall, how do we judge if it has sufficient energy to harm someone?  I arbitrarily decided that if it could punch through an IDPA cardboard target, it could hurt someone.  I don't know anyone who can drive a finger through a single sheet of corrugated cardboard.  Now, a finger isn't a bullet, but that’s my standard.

I would have loved to have a massive ballistic gel block to measure penetration, but I didn't.  Let me know if you would like to sponsor a second set of trials with ballistic gel.  I'm your man.

 

The following three rounds were utilized:

PMC Bronze 223 Remington, 55gr FMJ-BT

Hornady Varmint Express 223 Remington 55gr V-Max, polymer-tipped

Federal LE 5.56X45 mm 43gr Lite open tip- Match Frangible

The Federal Frangible needs a little explanation.  The bullet is a copper and tungsten powder core compressed in a copper gilding metal jacket.  These are typically used around objects that could be damaged by a solid bullet, like submarines, nuclear facilities, and CQC training with hard targets.

I didn't expect results with the first volley and used a crappy IDPA target

The results of the first three rounds were amazing.  The entry holes looked normal, but not the exit holes.  The results on cardboard looked interesting.  The PMC FMJ drilled the hole through both plaster walls and the cardboard.  The Federal Frangible exploded, tearing the rather raggy IDPA target I was using.  The Hornady plastic tip varmint round had started to fragment.

Then I realized my rounds had clipped the frame's top 2x4.

The 2x4 sat low in the frame and that's were my first three rounds went

Reshooting the rounds was less impressive.

The FMJ continued to drill holes in all my tests.  It became less important as a standard.  Anything I shot it through, the FMJ round made a round hole going in and coming out.  It just kept going.

I didn't reshoot the FMJ. 

The frangible round made the same size hole as the one which grazed the wood.  The varmint round made a slightly reduced hole and less push-out damage.  It appears the impact on just the plaster board provided the Frangible and polymer-tipped Varmint round with some of the deformation needed.

The Red tip has key-holed and the Frangible starting to come apart  

The cardboard target has a tale to tell, too.  The red plastic tip varmint round has started to tumble and punched a key hole through the cardboard.  The frangible round began to come apart and created small holes.

So far, the frangible round has the advantage.

I slipped a 0.75-inch-thick sheet of styrene foam insulation between the plasterboard walls.  I anticipated replacing the void between the walls with a material with different physical properties, hardness, elastic and flexible nature, as well as a different coefficient of friction, would alter the outcome with both the Varmint and the Frangible rounds.

I was right.  While the exit holes don't look different, you can see a big difference in the cardboard.  The frangible has blown out a huge center, reminding me of a small close-up shotgun blast.  The Varmint round has produced a cloud of penetrating shell fragments.

Exit wounds from insulated portion of wall

The dark coloration is the compressed metal power of the Frangible bullet 

The foam insulation, to my surprise, didn't look significantly damaged. 

I had to sit on the ground to shoot straight on to the wall.  The Frangible and red-tip Varmint rounds left similar holes in the paneling and have blown fragments of wood outward.

Exit wounds in the insulated and paneled wall

The drill-like PMC hole is found, the varmint round has started to fragment as shown by the irregular hole.  But the frangible round is turning into a high-energy cloud of metal powder. It appears the passage through solid material acts as a collar to restrain powder metal.  It's the exit picture that seems interesting.

The PMC remains a drilled hole.  The red tip Varmint round has fragmented.  Look at the damage from the Frangible round.

The frangible round still has sufficient energy to tear a large hole in cardboard.  Remember, the cardboard was about two feet behind the birch plywood.  Double the distance and the density of the metal cloud should drop to half.  The metal fragments from the Varmint round will remain the same size but should continue to separate from each other.

Let's explore one possibility in your home.  Your round misses the VCA (Violent Criminal Actor).  This round punches through the first plaster wall, encounters a sheet of foam insulation, a second plasterboard wall, and, as design might have it, a room lined with quarter-inch paneling or the back of an empty bookshelf.

It could happen.  You're a savvy gun owner.  You've picked points of interdiction where misses and shoot-throughs have the best chance of becoming harmless.

These results show that if you use a .223 for home defense, unless you have concrete walls, over penetration is a problem.  Frangible rounds are your answer.

We haven't discussed the medical impact of either Frangible and Varmint rounds.  I'm simply not qualified to discuss this, but I suspect having a metal cloud in a wound isn't going to be an easy procedure for the trauma surgeons.  The same could be true of the metal fragments from a varmint round.

Why should this matter?  The prosecutor will want to know "Why?  Why did you use this round and not any other round?"  Some of the best answers fall along the line of, "It was what I had available at the time I was attacked."  A better answer might be, "I chose that round to minimize danger to family members or neighbors who might be behind the VCA when he forced me to defend myself."

In the civil suit, the opposing lawyer will want to make it appear you wanted the misguided home invader to suffer, to be permanently maimed by your action.  Again, explaining to the jury that you selected these rounds to end the conflict as quickly as possible with minimal injury and with an eye on the safety of your family members and neighbors could be an essential key to your defense.

This is a subject you should consult your lawyer about, but don't let his idea of what will be an easy legal defense defer you from maximizing your survival.