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How Does a 300 BLK Suppressor Work?

300 Blackout deserves a suppressor. Let’s face it, the round was designed with this intent in mind. After all, few other (if any) rifle platforms and cartridge combinations can go from supersonic to subsonic, un-suppressed to suppressed, with just the threading of a can on the muzzle. If you don’t eventually invest in a suppress for your 300 BLK rifle or pistol, you’re missing out. If you’re reading this, though, we can be confident you’re interested. So, how does a suppressor, or “can”, work? Let’s find out:

Why Guns are Loud: Sonic Booms and Explosions

To understand how a suppressor works, we must clarify a simple concept, first: Why guns are loud. Why are they loud? Well, they’re loud for two reasons: One, (this pertains to supersonic 300 BLK only, and AR 15 rifles in general), the bullet being fired travels faster than the speed of sound. That means a sonic boom occurs after the bullet exits the barrel. This sonic boom is that signature “crack” you hear echoing across the range or valley.

Two, guns are loud, whether firing supersonic or subsonic rounds, because of the expansion of expelled gasses exiting the barrel alongside the bullet. If you’ve ever lit a firecracker or lit a campfire with gasoline, you’ve witnessed the physics behind why even subsonic guns (that do not cause a sonic boom) are still loud. That expansion of gasses is immediate. It’s literally an explosion that accelerates large quantities of air around it at high speeds. All that pressure and movement of air that makes your gun’s bullet zip along at x- hundred or -thousand feet per second also causes a lot of noise.

How Suppressors Quiet Things Down

Unfortunately, suppressors cannot prevent or mitigate the sonic boom caused by supersonic ammo. This boom happens after the round exits the barrel. But suppressors can, and do, quiet down that expansion of gasses exiting the muzzle. This is the basic premise for how a suppressor works.

300 Blackout Upper (16" Barrel & M-Lok Handguard) AR15 Complete Rifle Upper

Our 16″ M-Lok Upper features a universal 5/8 x 24 thread pitch, 1:7 twist, and carbine-length gas system for easy, accurate suppressed shooting

The Mechanics of a Suppressor

Suppressors are often called “cans”, but they’re not just hollow tubes of metal. Suppressors use complex shapes and designs to contain all that gas and slow it down. The pressure behind a bullet exiting the muzzle is intense – somewhere around 3,000 PSI. For comparison, the pressure in a champagne bottle is around 70 to 90 PSI.  Popping the cork from a glass of bubbly is pretty loud even at such low pressures, so you can start to see why a gunshot is deafening.

Anyway, suppressors need a lot of strength and science to confine all that pressure into such a small space and slow the release of that pressure just enough that it’s quiet, but not so slow that it’s destructive to the suppressor itself.

Inside of a Suppressor

Without getting into the details too much, a suppressor uses a system of baffles, chambers, and geometrically shaped metal bits to direct the flow of gas inside the suppressor, slowing it down and allowing the gas to expand without a deafening bang. The end goal of a good suppressor is to let that gas escape at just the right time – once it’s expanded and slowed down to a quiet “whoosh”.

300 Blackout Pistol Upper (10.5" SS Barrel & M-Lok Handguard) AR 15 Complete Pistol Upper

Our 10.5″ SS Pistol Upper, equipped with a pistol gas system and universal thread pitch, makes the perfect close-quarters weapon once suppressed

300 BLK With a Suppressor is Awesome

If you haven’t seen and heard examples of 300 BLK AR 15s using suppressors and firing subsonic ammo, go find some videos right now. You’ll be amazed at just how quiet your black rifle can get with a can threaded to the muzzle. Once you’ve realized how badly you want one, check out our suppressor buying guide – it’ll help you get your hands on one!

DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At 300-blackoutupper, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.


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