Quieter 300 Blackout

General silencer discussion. If you want to talk about a specific silenced rifle or pistol, it is best to do that in the rifle or pistol section for that brand.

All NFA laws apply.

Moderators: mpallett, mr fixit, bakerjw, renegade

Post Reply
cspradlin
New Member
Posts: 4
Joined: Sat Feb 20, 2016 10:23 am

Quieter 300 Blackout

Post by cspradlin »

Have a 300 Blackout AR with 8" barrel suppressed with Silencerco Omega. Direct gas. My 220 grain subs are avging 925 fps with A1680. I know it won't be Hollywood quiet, but I'm getting loud pop like slapping dirty sneakers on a sidewalk. Does not hurt my ears. Is there anyway to make it a little quieter? I have a heavy JP silent captured spring on the way.
User avatar
curtistactical
Silent But Deadly
Posts: 469
Joined: Fri Apr 25, 2014 9:22 am

Re: Quieter 300 Blackout

Post by curtistactical »

The Omega is a great suppressor, you can get it quieter but my advice if you want it under 120db an integral suppressor is the way to go. The quietest 300blk we have ever built was a ported 8" barrel that ended up at 14.5" with the suppressor, it metered 118db with Remington 220gr ammo. With the ported barrel the Remington 220gr averaged 890fps.
Joe
Joseph Jones
Curtis Tactical
07/02
User avatar
MJF1911
Silent But Deadly
Posts: 523
Joined: Mon Sep 26, 2011 11:40 pm
Location: Montana Territory

Re: Quieter 300 Blackout

Post by MJF1911 »

I feel like mine was quieter with AA5744 than with A1680, its also a significantly cleaner.
SWR 556 Specwar, 762 Specwar, Octane 45HD, Spectre II; SilencerCo Osprey 45, Omega; AAC Pilot, 300TM; Ruger AC556
Rugged Oculus; Dead Air Sandman K
User avatar
eastern_hunter
Silent But Deadly
Posts: 966
Joined: Sat Nov 21, 2009 8:34 pm
Location: Charleston, WV

Re: Quieter 300 Blackout

Post by eastern_hunter »

Propellant choice is the next step in finding quiet. You're looking for the propellant that yields the lowest bore exit pressure ... it will be the quietest. One approach is to find the fastest powder that will yield the desired velocity thus giving the least pressure at the muzzle.

The challenge is to find that fastest powder that will also not be prone to detonation (SEE) when small volumes of it burned in a relatively large case volume.

The fastest powder I've tried is 2400. Is faster than AA5744. (I have 2400 for handguns and AA5744 for cast projectiles in very large cases.) 2400 burns much cleaner than AA5744 and seems pretty quiet.

Changing the buffer spring arrangement will make a significant reduction in the noise you hear next to your right ear. Am not sure that noise can be heard very far away though.
Coltm4
Silent Operator
Posts: 70
Joined: Tue Jul 04, 2006 12:06 am

Re: Quieter 300 Blackout

Post by Coltm4 »

eastern_hunter wrote:Propellant choice is the next step in finding quiet. You're looking for the propellant that yields the lowest bore exit pressure ... it will be the quietest. One approach is to find the fastest powder that will yield the desired velocity thus giving the least pressure at the muzzle.

The challenge is to find that fastest powder that will also not be prone to detonation (SEE) when small volumes of it burned in a relatively large case volume.

The fastest powder I've tried is 2400. Is faster than AA5744. (I have 2400 for handguns and AA5744 for cast projectiles in very large cases.) 2400 burns much cleaner than AA5744 and seems pretty quiet.

Changing the buffer spring arrangement will make a significant reduction in the noise you hear next to your right ear. Am not sure that noise can be heard very far away though.
This.

Suggested loads can be found here: http://quarterbore.com/300whisper/subsonic.html

Notice the ability to use 168/165 gn projectiles in a subsonic load. 2400 cycles my 10.5" suppressed.
User avatar
TROOPER
Silent But Deadly
Posts: 7441
Joined: Thu Aug 23, 2007 1:24 pm
Location: Augusta, Georgia

Re: Quieter 300 Blackout

Post by TROOPER »

Is it appropriate to treat sub-sonic 300 BLK as a pistol cartridge? Mind you, I'm not arguing for or against this, it just always struck me as, in essence, a pistol cartridge given the size and weight of the projectile, as well as the desired lower velocity, and all in conjunction with the shorter barrel. Well... short for a rifle.
brut28481
New Member
Posts: 6
Joined: Mon Jan 11, 2016 11:00 am

Re: Quieter 300 Blackout

Post by brut28481 »

Coltm4 wrote:
eastern_hunter wrote:Propellant choice is the next step in finding quiet. You're looking for the propellant that yields the lowest bore exit pressure ... it will be the quietest. One approach is to find the fastest powder that will yield the desired velocity thus giving the least pressure at the muzzle.

The challenge is to find that fastest powder that will also not be prone to detonation (SEE) when small volumes of it burned in a relatively large case volume.

The fastest powder I've tried is 2400. Is faster than AA5744. (I have 2400 for handguns and AA5744 for cast projectiles in very large cases.) 2400 burns much cleaner than AA5744 and seems pretty quiet.

Changing the buffer spring arrangement will make a significant reduction in the noise you hear next to your right ear. Am not sure that noise can be heard very far away though.
This.

Suggested loads can be found here: http://quarterbore.com/300whisper/subsonic.html

Notice the ability to use 168/165 gn projectiles in a subsonic load. 2400 cycles my 10.5" suppressed.
+1 on powder choices (also +1 on Curtis Tactical Cans!) I have hand loaded a wide range of powder/projectile combinations and found the correct balance of burn rates/gas/cycling ability plays a a big role in perceived sound & cycling AR. I have tested 4198, 4227, Reloader 7, 1680 & AA#9 and found AA#9 to be the cleanest & quietest powder (magnum pistol powder). The other powders don't fully burn, are dirty or very gasey. There is a ton of people on the handloading section of http://www.300blktalk.com/forum/viewforum.php?f=141 with a lot of great research/load combinations. I run a 10.5", Suppressed (Curtis Tactical Rebaffled Kestrel .308), SLR Adjustable Gas Block, JP Silent Capture. One of my quietest 190gr-220gr loads is 7.1gr-7.3gr AA#9 anywhere from 950-1050 depending on projectile.
BlogSarge
Silent Operator
Posts: 85
Joined: Sun Nov 01, 2015 12:46 pm

Re: Quieter 300 Blackout

Post by BlogSarge »

TROOPER wrote:Is it appropriate to treat sub-sonic 300 BLK as a pistol cartridge? Mind you, I'm not arguing for or against this, it just always struck me as, in essence, a pistol cartridge given the size and weight of the projectile, as well as the desired lower velocity, and all in conjunction with the shorter barrel. Well... short for a rifle.

I always consider subsonic 300blk rounds as a 45acp with more streamlined bullet. Bullet weight and velocity very similar, ballistic coefficient much better.
User avatar
Capt. Link.
Silent But Deadly
Posts: 2829
Joined: Wed Oct 17, 2007 9:05 pm
Location: USA.

Re: Quieter 300 Blackout

Post by Capt. Link. »

Changing the weight of the projectile may allow more complete combustion and eliminate the pop.A faster powder should do the same.Can you regulate or turn off the gas to "hear" if that makes a difference.That could tell you if the spring upgrade or a heavy buffer will help.
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
Elkins45
Senior Silent Operator
Posts: 140
Joined: Tue Mar 19, 2013 8:17 pm

Re: Quieter 300 Blackout

Post by Elkins45 »

I have found AA#9 to be noticeably quieter than any of the other magnum pistol powders I have tried, and I also catch a lot less blowback in my face. As a lefty this really matters to me, since I'm staring right into the ejection port with half my face every time I pull the trigger.
User avatar
whiterussian1974
Silent But Deadly
Posts: 2857
Joined: Sat Sep 28, 2013 11:37 pm
Location: On 8th line of eye chart.

Re: Quieter 300 Blackout

Post by whiterussian1974 »

TROOPER wrote:Is it appropriate to treat sub-sonic 300 BLK as a pistol cartridge? Mind you, I'm not arguing for or against this, it just always struck me as, in essence, a pistol cartridge given the size and weight of the projectile, as well as the desired lower velocity, and all in conjunction with the shorter barrel. Well... short for a rifle.
Yes. Same speed/weight combo as my .40SW. 165/180/200gr @ 950-1085fps.

Just less initial frontal area.
The Darkest Corners of Hell are reserved for those who remain Neutral!-Dante
The Death of One is a Tragedy, a million only a statistic.-Stalin
silencertalk.com/forum/viewtopic.php?f=10&t=135314
User avatar
eastern_hunter
Silent But Deadly
Posts: 966
Joined: Sat Nov 21, 2009 8:34 pm
Location: Charleston, WV

Re: Quieter 300 Blackout

Post by eastern_hunter »

Interesting ... AA#9 is slightly faster than 2400. Would probably have tried it too if I had any. Used the last of it some time ago ;-) Good powder for medium loads in 41 and 44 Rem Mags. Generally cleaner burning than 2400.
Elkins45
Senior Silent Operator
Posts: 140
Joined: Tue Mar 19, 2013 8:17 pm

Re: Quieter 300 Blackout

Post by Elkins45 »

#9 is my preferred powder for heavy bullets in the 10mm so I try not to run low. It is becoming one of my favorite powders.

I'm going to try Power Pistol and Longshot in some heavy 300 blackout subsonic loads as well to see if there is a noticeable difference.
Dolomite_Supafly
Silent Operator
Posts: 89
Joined: Fri Oct 30, 2009 6:03 am
Location: E. TN

Re: Quieter 300 Blackout

Post by Dolomite_Supafly »

Powder choice can have a HUGE impact on noise levels at a given velocity. You want the fastest burning powder that will cycle the gun at the desired FPS. And for most that is several steps faster than A1680.

I have also metered powders against each other. I cannot measure actual dB but I can compare loads to loads. The quietest for my was IMR 4227. It was also least sensitive than Lil'Gun, H4198 and a off brand version of A1680. It is with MY silencer.

I started testing some other powders and Blue Dot works great in my gun. In a barrel longer than 10.5" the rounds will go supersonic in winter. But in summer they are amazing loads. I believe they are even quieter than my IMR 4227 loads.

Power Pistol is too fast to cycle an AR, I have tried. BTW, I had a friend try black powder and it ran fine.
It is natural to man to indulge in the illusions of hope. We are apt to shut our eyes against a painful truth-and listen to the song of that siren, till she transforms us into beasts

Patrick Henry
Fulmen
Silent But Deadly
Posts: 1045
Joined: Wed Feb 04, 2009 6:36 am

Re: Quieter 300 Blackout

Post by Fulmen »

The fastest powder I have used with 220's is N110, N105 could possibly work, but I don't like to get too close to maximum without measuring pressure. Sadly the round is too short for it to work with pressure trace in most guns. But the difference in charge weight is insignificant, so I haven't bothered with it.
TROOPER wrote:Is it appropriate to treat sub-sonic 300 BLK as a pistol cartridge?
Sure, why not? It's a sliding scale, not some fixed division.
Post Reply