I do not want Smarter Every Day to be observed as

a channel that glorifies weaponry.

I am just fascinated by fluid dynamics,

ballistics, optics,

mechanics, aerodynamics.

All this stuff is just fascinating to me.

And I am hard-pressed to find one singular thing

that I can study that wraps all these physical phenomenon

into the perfect Venn diagram that tickles my brain

quite like firearms.

So, that's why you'll see me studying firearms so often

and I hope you realize that I'm doing it as intelligently

and respectfully as I can.

That being said, I've made some observations

in the last episode and I've learned some stuff.

And I've also decided to push it a little further

by studying suppressors.

So, let's look at this and try to get smarter everyday.

First, let's revisit what we learned in the last episode.

Using a phantom camera with a clever photography technique

called Schlieren, which is German for streak by the way,

we observe that the supersonic bullet creates

an angular shot cone and the angle of that cone can

be used to determine the mach number.

We also learned from Dr. Konigstrasse at UAH

that a bullet travelling in the transonic regime

can create supersonic flow around it

because the air has to speed up

and rush around the outside of the surface of the bullet.

This is a connection I didn't make at the time

but we've all see these awesome pictures

of a fighter jet with this cone of vapor behind it,

this is totally why that happens.

The jet is flying along in the transonic regime

just like that bullet and just like the normal shockwave

that occurs on the side of the subsonic bullet

that's happening on the jet.

And it does two things, number one,

it makes this cone of vapor form on the jet

and number two, it makes me all tingly inside.

Okay, so I think we have a good understanding

at this point of shockwaves created by a bullet itself.

You may have heard someone talk about the crack of a bullet

as it passes, that's created by this shockwave.

But if you think about the bang of a gunshot,

it's all those rapidly expanding gases

out the front of a muzzle right?

So it's time to hone in on that area right there

and study that with super schlom,

super slowmo suppressor Schlieren, there you go.

It's hard to say.

In a past episode of Smarter Every day

I asked a company to fabricate a see-through suppressor

so we could see the flame front propagate

through the baffles and try to understand what was going on.

That was effective in showing what happens on the inside

of their particular suppressor design

but what I wanna see is exactly what happens

on the outside of the suppressor,

after all, that's where all the noise is.

Here's my friend Coop firing his rifle

chambered in 300 blackout, both suppressed and unsuppressed.

I want to show you a full minute of slow motion video

because I believe it does the best job of explaining

the physics of what's going on.

On the left we have a suppressed weapon

and on the right we have the same weapon unsuppressed.

When they're first fired you can see straight away

that the weapon on the right seems to have a larger,

dirtier blast but after four milliseconds

there doesn't seem to be any more shockwaves,

we're just venting the exhaust gases at that point.

The weapon on the left, however, is still chugging away.

It's like this initial blast is bouncing around

on the inside of the suppressor

and just a little bit of the gases

are being leaked out with every reverberation.

(gunshot echo)

Watch what happens next though.

On the right, the echo from the unsuppressed weapon

is huge and very distinct.

You can see how powerful and singular

that initial blast was

by how sharp the echo is when it returns.

Imagine that echo entering your ears,

meanwhile you can still see that the suppressed weapon

is dissipating that acoustic energy slowly.

This is like the clearest example I can show

of that energy being dissipated differently.

On the right, the unsuppressed version,

the whole thing's over in a millisecond and a half

but on the left, the same acoustic energy

is dissipated over 15 milliseconds.

That is a direct comparison showing you

that it almost acts like a capacitor in a circuit,

it's like, slowly filtering the energy as it exits.

Anyway, that energy dissipation does not come for free.

Suppressors heat up very, very quickly.

All that thermal energy is captured

because it doesn't dissipate away from the weapons.

So the problem with suppressors is

if you fire enough rounds through 'em,

they heat up very, very fast and they can cause malfunctions

and even damage to the weapon.

Now let's look at subsonic ammunition

being fired from a suppressor.

This is absolutely fascinating.

Okay first observation.

The first thing that leaves the suppressor is unburnt powder

and look at that, there's little baby shockwave,

they're supersonic.

Now whether this is gunk coming loose

from previous shots, or whatever, I don't know

but it's clearly supersonic.

Second, did you see that little vortex ring

poot out the end?

Okay, here we go, bullet time.

We know this is a subsonic round

so we're expecting normal shockwaves

on the sides of the bullet but look at that.

They're not there until the bullet

is several inches away from the muzzle.

It is crazy to think about how complicated

this flow environment is but it's really fun

to make these observations and try to figure it out.

This episode of Smarter Every Day is sponsored

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I really like it when this happens

and yeah, give it a shot.

I think you'll dig it with your family, it works for us.

What are these little squirrely things

that come out of the suppressor?

- Okay, so what you're seeing here

on this blackout cartridge is your seeing unburnt

propellant leaving the muzzle before the bullet goes

and so for 300 blackout optimally you get complete

burnout around 9 1/2 to ten inches of barrel length.

So this is a 10.2 inch barrel length

so we're right on the threshold of burning

all the propellant out before the bullet leaves the muzzle.

- But look, there was a supersonic piece of powder

- Yeah there is.

- You see that?

- Whoa!

- This is insane, we're just like, learning important stuff.

Alright, well that was delightful,

what did we learn John? (laughs)

- Propellant outruns bullets sometimes.

You may have grains of propellant

that exit the muzzle faster than the bullet, supersonically.

- That's crazy, and there's a shockwave on those grains

of propellant - Exactly!

- That's uh, never would have thought that.

- Neither would I.

- I hope this episode earned your subscription.

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You're a smart person, you can make your own decisions.

I'm Destin, you're gettin' smarter every day.

Have a good one.