300 blackout subsonic

[Sniper338]

I just loaded a few rounds:
7.5 inch barrel pistol upper
Lake city brass
Cci 400 small rifle
200gr hornady ELD-X
AA1680

Charges:
11.0
10.0
9.0
8.0
7.0
5.0

With the suppressor on (9 inch thunderbeast direct thread) this AR is still loud... doesnt compare to my 308 subsonic, sound wise... of course its not the standard gunshot sound, more like slamming a book down on a concrete floor real hard kind of sound...

I dropped all the way to 5.0 grains, it didnt eject, but my buffer isnt set up for subsonic yet either..

5.0 gr was much better, but still have to go lower if i want to just hear the action and have an actual "pretty quiet" shot...

So far im not too impressed with the 300blk suppressor hype at all...

What are yall running powder/grain wise subsonic for suppressors?

 

[Homerange]

Cartridges of the World: 220 gr, IMR 4198, 11.5 gr of which you'd need to go a little lower for a 200 grainer. (1036 fps)
ADI Handloaders Guide: 208 gr, AR2207, 11.2 gr ; quite low pressure @ 18,800 CUP for 1042 fps.
AR2207 xrefs to H4198, RL7, W680, IMR 4198

Don't own one but guys that have used them here for subsonic work were all using 220 gr pills.

 

[gary0529]

I run mine through a bolt action XR receiver and use 220, 240 and even have some old 250's that I mostly run with Lil'Gun, IMR4227 or H110 They are all VERY quiet .
I have no idea on how well or if they will cycle an AR.

Gary

 

[Geno C]

In general the ar will be louder than a bolt of course. Super cold weather affects the speed of sound. What is the velocity you're at?

When I want to run really quiet, I either turn of the gas and just run it with the side charger or grab the bolt gun. I use H110 mostly. I have a bit of lilgun I might try in the future though. I couldn't find 1680 when I first started and now that I have some I don't see a need to switch to it.

 

[rebel]

ARs are quite a bit louder than a bolt gun. If you really want to hear how quiet it is, have a friend shoot it and stand first on the non port side and then the other. Surprising how much noise comes from that action, which is right in your face. 10.5 gr of 1680 is what I run behind a 200 gr. Lapua sub bullet. 1680 is the powder for great function for an AR, However -
It is a "loud" powder
It is a dirty powder when run subsonic
It actually works great for heavy supers and takes compression well.
If you can lay your hands on some N110 you will have the Holy Grail of sub powders IMO. Runs clean and is much quieter.
Questions about your build - Do you know your gas port size? This will help assess function. If you were operating the bolt and cycling another round below 9 grains, it's a good chance you are over gassed and need an adjustable gas block. It's a problem with a lot of barrel mfg. but easily remedied.
I would say at 5 gr. of 1680 you are fairly close to sticking a bullet. Keep your charge at around 10 to 11 grains. Have you chronographed these loads yet? Depending on where you are your higher load could have gone Mach 1.
edit - Here is some more help http://www.300blktalk.com/forum/viewtopic.php?f=141&t=81567

 

[Jdne5b]

At 5gr, I would question stability or even making it out of the barrel.. Hopefully you tested before taking the chance of running a 200gr slug down your Thunderbeast side ways. Maybe all that noise was a bullet banging down the sides of the can.

Where you are testing it also has an impact on how it sounds. Testing indoors, or in the woods is much louder than an open field.

The AR won't be the click sound you're used to with the bolt gun though.

 

[wedgy]

Get an adjustable gas block and they make a softer spring.
http://www.brownells.com/rifle-part...blackout-carbine-buffer-spring-prod56149.aspx
https://nemoarms.com/store/300-blackout-custom-carbine-buffer-spring/
Those loads are really low, make sure the barrel is clear before you shoot another one.

 

[EOD Rob]

Sniper338,
If there is one thing I have found about the 300BO is that you better be ready to spend some time when you are working up loads for this thing! First, decide what bullet you want to run and stick with it. Second, be ready to try several different powders. Below is a list with charges (Subsonic) i found to work well in my 16" bolt gun. I did not spend much time with my gas gun, since I figured I will just run the same in the gas gun as the bolt. If you would like supersonic data, just PM me! That was a whole other rabbit hole.

All of these loads are with Hornady 208gr A-Max at 50yds

AA1680- 11.0gr .436" average of three groups, 1046fps
H110- 9.0gr .470" average of four groups, fps unknown
IMR-4198, 11.0gr-10.0gr no data due to looking like a shotgun blast
IMR-4227 no data due to looking like a shotgun blast.
Trailboss- have not tried yet. one to look at!

In closing, my experience with sub 300BO has been a ride, but dont get discouraged. Maybe its because Im running a bolt that is very finicky. Guess this is what you sign up for as a reloader!

 

[archerforkids]

At 5gr, I would question stability or even making it out of the barrel.. Hopefully you tested before taking the chance of running a 200gr slug down your Thunderbeast side ways. Maybe all that noise was a bullet banging down the sides of the can.

Where you are testing it also has an impact on how it sounds. Testing indoors, or in the woods is much louder than an open field.

The AR won't be the click sound you're used to with the bolt gun though.

This is IMPORTANT info here. I do all my subsonic load development without my suppressor on, target at about 25 yards so I can check for keyholing, and over a chrono. Darn suppressor cost waaaaay to much to be taking a chance.

 

[Teamjon]

This is IMPORTANT info here. I do all my subsonic load development without my suppressor on, target at about 25 yards so I can check for keyholing, and over a chrono. Darn suppressor cost waaaaay to much to be taking a chance.

I am running a 7.5 " ar pistol, 220 g berry plated bullets, World Shooters blackout powder,. small rifle primers, and Starling brass. I am getting key holing at 15 to 16 g of powder, what do you think

 

[Teamjon]

I am running a 7.5 " ar pistol, 220 g berry plated bullets, World Shooters blackout powder,. small rifle primers, and Starling brass. I am getting key holing at 15 to 16 g of powder, what do you think

plus a Nomad 30 suppressor

 

[archerforkids]

I would question if that short a barrel will stabilize that bullet, but will also say my lack of experience is showing here. You should try some 180s. You might be pleasantly surprised.

 

[dellet]

I am running a 7.5 " ar pistol, 220 g berry plated bullets, World Shooters blackout powder,. small rifle primers, and Starling brass. I am getting key holing at 15 to 16 g of powder, what do you think

Barrel length is no problem, COL of the cartridge would be a good place to start.

First guess is compressing the powder and deforming the bullet.
Second guess is pushing that bullet too hard. Excessive pressure and speed. It’s rated to 1300 FPS. Good chance your over that at 16 grains.

Your at the very top end of the load range for that bullet. A little bit of a rough bore and the plating will start to peel.

 

[Oso]

I am running 8.25" barrel (1:8 twist) shooting 195gr BTHP. I have loaded subsonics with H110, N110, and CFE Black (ie 1680 clone with a copper defouler agent). I'm glad I only bought a couple of pounds of CFE Black to test... not worth its time for subsonic or supersonic.

For Subsonics both H110 and N110 performed consistently with good results out of short barrel (1 inch at 50 yards). The powder charge is within .5gr between the two powders. N110 burns cleaner and performance-wise edges out H110, but you pay a premium price.

300BO chamber is designed with a large jump (similar to a pistol caliber). With the magazine length restriction for AR15, you can't load bullets long to reduce some of this jump. If you are using factory 5,.56 PMAG's then your subsonic COAL will need to be shorter (approx. 2.16") in order to provide clearance for the long/wide bullet ogee of subsonics and the internal ribs in the magazine. The easiest solution to eliminating need to load subsonics short is to buy dedicated 300BO Mags (no internal 5.56 rib), which allow you to load all bullets to mag length. Less jump may translate into improved performance and may help stabilize it better.

 

[Park ranger]

Get your velocity to 975 -990 fps. Above 1000 fps you will start getting echoes down range in normal weather. In other words, as long Range and sub sonic shooters know, Mach .8 to 1.2 is a weird zone to be in.

if you have a pistol gas tube, 7.4 of lilgun will function and be very quiet with a 210-220 grain bullet. Killing the gas, as said above will make it less loud at your face. If you don’t need your AR to fuction , you could even go with a faster powder like red dot in the 5 grain range.

I think 11 grains of powder is asking too much to condition, go with faster powder.

 

[22DASHER]

I just loaded a few rounds:
7.5 inch barrel pistol upper
Lake city brass
Cci 400 small rifle
200gr hornady ELD-X
AA1680

Charges:
11.0
10.0
9.0
8.0
7.0
5.0

With the suppressor on (9 inch thunderbeast direct thread) this AR is still loud... doesnt compare to my 308 subsonic, sound wise... of course its not the standard gunshot sound, more like slamming a book down on a concrete floor real hard kind of sound...

I dropped all the way to 5.0 grains, it didnt eject, but my buffer isnt set up for subsonic yet either..

5.0 gr was much better, but still have to go lower if i want to just hear the action and have an actual "pretty quiet" shot...

So far im not too impressed with the 300blk suppressor hype at all...

What are yall running powder/grain wise subsonic for suppressors?

Switch powder

 

[Oso]

Instead of a shotgun powder (dirty), you could also consider using pistol powder. On my list of things to try is subsonic load development with TiteGroup or Bullseye for my shorty. Careful conservative load development.

My 18" CZ bolt gun shoot 1/2" groups with N110 at 50 yards so that is dialed in and not worth changing.

 

[Jet]

I4227 running at 1050fps and Berrys 220 gr provides excellent accuracy and reliable function out of my 10.5” barrel and a Surefire can on.

 

[Knotwild]

Bullseye sounds just a little scary. I've used it for decades in .45 acp, but I don't think so. There are too many better options.

 

[Oso]

I think if you start with similar load for 45acp then TiteGroup or Bullseye shouldn't be a problem. Work up from there is small conservative increases. I did a bunch of fire forming 223AI cases using the Cream of Wheat Method using 8.5gr-9.0gr Bullseye with remainder of case filled with cornmeal and a patch to plug the neck. Rifle chambers are stronger then a pistol chamber. Also, I'm not concerned about a pressure spike because of the significant jump that bullet must make to reach the lands when loaded to mag length in AR15.

There have been some discussions that in a super short barrel (shorter then 10") a true pistol powder may be the right answer for subsonics (fast, clean burn). Potential to edge out N110 and H110.