Suppressed .300 Blackout Rifle Build

The shorter barrel won't necessarily be any different in terms of accuracy, but it will make a significant difference in velocity for the same given round. You do plan to go with pistol gas, right? Making the BLK a SBR changes the animal somewhat. It's much better for shooting subs, and suppressed will be a really quiet rifle. If you go with a carbine barrel and gas, you can still shoot subs, but it becomes more difficult to get reliable cycling and still keep the velocities subsonic. Not terribly more difficult, you just have to pay more attention to the bullet weight and powder loads, because you're going to get more velocity from the longer barrel.

I built a carbine length 300BLK, didn't do the paperwork (yet) for the suppressor, but I get to shoot my cousin's SBR suppressed BLK, so I can compare between them. The SBR is awesome for handling, with his can in place, it's just a couple of inches longer than my carbine, and lighter. Of course, the weight has some to do with the parts we used. My carbine barrel is a Rainier Select Match 16" with carbine gas port, it's heavier than his 10.5" barrel and suppressor together. My fore end is also longer than his, so it's heavier also. My carbine, complete with sling and scope weighs in at 8.25 pounds, his SBR with suppressor, is about 7 and a few ounces.

A Noveske or Shilen barrel is about the best you can get. Rainier's Match barrels are made from Shilen blanks.

There's a great forum for Blackouts, you can find pretty much anything you need to know about them and the ammo.

http://www.300blktalk.com

Tagg want to see where this goes

I went with a DPMS 16" upper for my .300 B/O build then aded a MI free float tube. Suppressed with full power loads she is a sub moa shooter out to 200 yards and very quiet for supersonic rounds. For a trigger I went with the Geissele SSA-E trigger which is awesome!

horsemen61 said:

Tagg want to see where this goes

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TIMC said:

For a trigger I went with the Geissele SSA-E trigger which is awesome!

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Geissele's stuff is killer. My fore end is a Geissele, and I have his High Speed National Match DMR trigger in mine. Pricey, but well worth it.

Your rifle looks great.

Regarding Barrel Length, I thought the BO round didn't lose much velocity even with barrel lengths down to 8" or 9"? If that's true then, as long as you don't mind the 2nd stamp for SBR, you could keep the total length (with the can attached) pretty short.

I've been playing with a BO with a 9 12 inch barrel and YHM suppressor. I've found that hunting with this setup leads to a problem. To stay subsonic, I'm loading a 200 fmj Lapua bullet averaging right at 1,000 fps. At this speed, the bullet will punch a nice pencil sized hole through a hog without much damage. i shot 3 a few mornings ago and had to shoot them with a 9mm to finish them off as they were still on their feet.
I'm sure a lighter bullet at a highter speed would perform better with this round in a hunting situation, but there lies the problem of staying subsonic.
I kill hogs regularly with a .223 fmj, and placed in the shoulder area they are one shot propositions, but they are traveling a lot faster when they hit the animal.
I love shooting the suppressed 300 Blackout, but I think I am going to relegate it to fun shooting and forget hunting with it.

Stony said:

I've found that hunting with this setup leads to a problem. To stay subsonic, I'm loading a 200 fmj Lapua bullet averaging right at 1,000 fps. At this speed, the bullet will punch a nice pencil sized hole through a hog without much damage.

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This is the problem with many high BC bullets at subsonic velocities = zero expansion. Barnes and Remington are supposedly working on 200gr + .308 bullets that will expand at 1,000 fps. The challenge with the .300 AAC Blackout subsonic is that bullets need to be heavy enough (enough powder/gas) to be able to cycle the action. They need to have an ogive that imitates the neck (at a specific distance from the case head) of the .223 Rem case in order to feed well in .223 Rem magazines. They also need an OAL that mimics the .223 Rem in order to feed well. The result is that the high BC bullets that meet the criteria listed tend not to expand at < 1,000 fps. I wonder if those using bolt action .300 AAC Blackout rifles are working up subsonic loads using bullets better suited to hunting.

Using the longer barrels makes the whole proposition just that much tougher, as you tend to pick up more velocity and go supersonic easier. I was playing with some of the same loads I am using in a Handi Rifle, and they would not stay subsonic. It's a fine balancing act between bullet weight, powder charge, and barrel length. It's been interesting though...especially since you can't hardly find the powders you want to use.

Stony said:

I love shooting the suppressed 300 Blackout, but I think I am going to relegate it to fun shooting and forget hunting with it.

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Why not use supersonic loads? Those will be much better for hunting.

Using the supersonic loads sort of defeats the purpose of using a suppressor. I have lots of rifles I can hunt with, but the reduced noise and blast of the suppressed load was the whole reason I set up this rifle in the first place. Hopefully the bullet guys can come up with a bullet that will do some more damage at the lower velocities. In the meantime I can enjoy shooting targets with it...as it is fun to shoot.
I originally thought I'd set up my night vision on this rifle, but I guess I'll just leave it on another one in .223 as that does a nice job on late night hogs.

Lehigh Defense has supposedly redesigned their subsonic 194gr Maximum Expansion load to feed better in ARs. If you aren't using an AR they also have their Controlled Fracture load. I haven't used either but talked to a few guys who like them.

Apparently, there is also an Outlaw Bullets making an expanding soft-nose lead bullet in .300; however it looks like the BC on that is nothing close to a 220gr SMK.

No free rides I guess - hard to get high BC and expands at subsonic velocity in the same package.

Stony said:

Using the supersonic loads sort of defeats the purpose of using a suppressor.

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Not at all. I've found this to be one of the most common misconceptions about suppressors: The myth that you need to use subsonic ammo. Sure, they're quieter with subsonic ammo, but even with supersonic ammo it's a lot quieter with a silencer than without.

You already have the suppressor, so have you tried shooting supersonic ammo through it? Normal 5.56/.223 ammo suppressed is quieter than a .22, and supersonic 300 Blackout is a little quieter than that. Sure, if you want maximum quietness you need to use subs in your 300 Blackout, but you're also handicapping yourself. Everyone I know who hunts with a silencer uses normal supersonic hunting ammo.

I've played with super and sub sonic through both of my rifles and just prefer them to be on the quieter side. I use a suppressor or .223 occasionally also, and while it seems somewhat quieter it doesn't seem like much like the effort. With the .223 it seems like the actual crack of the round is downrange a little and not as close to me....maybe it's just my imagination.

Stony said:

I've been playing with a BO with a 9 12 inch barrel and YHM suppressor. I've found that hunting with this setup leads to a problem. To stay subsonic, I'm loading a 200 fmj Lapua bullet averaging right at 1,000 fps. At this speed, the bullet will punch a nice pencil sized hole through a hog without much damage........
I kill hogs regularly with a .223 fmj, and placed in the shoulder area they are one shot propositions, but they are traveling a lot faster when they hit the animal.

I love shooting the suppressed 300 Blackout, but I think I am going to relegate it to fun shooting and forget hunting with it.

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You won't get any expansion with FMJ, regardless of velocity or bullet weight. And a 200 grain bullet at 1000fps will probably penetrate further than a 75 grain bullet at twice the speed. Upon contact, a light bullet gives up its energy much faster than a heavier one, less inertia due to lower mass.

Agreed with not having to shoot subs with a suppressor; obviously a suppressor will not decrease the sound of the supersonic shock wave, but it will substantially decrease the overall "footprint" of the discharge, and a 30-40 dB decrease is significant. My cousin and I have played with his 5.56 SBR (10.5" barrel) and my 300BLK carbine (16" barrel) shooting his gun with supers suppressed and unsuppressed, and subs suppressed and unsuppressed and my BLK with unsuppressed subs and with supers. The differences are pretty impressive, shooting his gun with supers and a suppressor, and shooting mine with subs unsuppressed. It's pretty close to the same, the difference is mainly in the pitch. His smaller caliber discharge has a higher pitched "crack", and mine is a lower pitched "pop", but both are noticeably quieter than unsuppressed supers from either gun.

The BLK's beauty is the versatility of the round, whether you're shooting from a short barrel or a carbine length. You can go from suppressed heavy subs from the short barrel, to lightweight supers from the carbine, and still have an effective platform out to a couple hundred yards for one and to around 400 yards for the other. Velocity does differ somewhat with the same load from the different barrel lengths, it's a matter of physics. The difference might not be as great as other calibers, because even the highest velocities are "only" in the low 2000 fps range with the BLK.

Most of the guys on the BLK forum who hunt seem to use something in the 125-150 grain range and drive them as fast as they'll go, to get the better expansion. Up to recently, most .308 spitzer bullets for hunting were designed for best expansion at velocities that the BLK just couldn't reach, but there are new ones coming out that expand better at lower velocities. I'm only punching paper and shooting silhouettes with mine, I typically load 155 Palma Match Kings to about 1850-1900 fps, and can knock down steel pigs at 300 yards, so they have a pretty good punch even at that range. I've only messed with subs enough to see at what powder load I can stay subsonic and still cycle my action. I'll eventually go the suppressor route, but now, I'm just having a ball with mine shooting middleweight supers.

TIMC,

I have a buddy that went with an already assembled 16" upper in 300BLK. It had a carbine gas system and even with an adjustable gas block added, we had to reduce weight in the buffer to get it to cycle sub sonic rounds, even with the can. Did yours run right out of the box?

Bullnettles said:

TIMC,

I have a buddy that went with an already assembled 16" upper in 300BLK. It had a carbine gas system and even with an adjustable gas block added, we had to reduce weight in the buffer to get it to cycle sub sonic rounds, even with the can. Did yours run right out of the box?

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What buffer did his upper have to begin with, and what powder was being used? Some faster powders loaded down to subsonic won't make enough gas to cycle the action, even with the additional back pressure of the suppressor.

I have to use a standard carbine buffer for my gun to cycle with the subs I load (200Gr Nosler, 11.5 gr. AA1680). If I use an H buffer with that load, it will eject the brass but won't feed another round. Playing with buffer weight and powder load is how you find what will and won't work. I haven't loaded subs any heavier, but I suspect that a 220 with a powder load that would keep it just under sonic would cycle with the H buffer, but I'd still go with the lighter one for the sake of reliability. I'm also using an adjustable gas block, I keep it wide open for now, the adjustability may come in handy with a can in place. For my usual 155 supers, I use an H buffer. Slows the cycling a little, almost completely kills the recoil. I imagine I could even use an H2 buffer, but haven't tried it yet.

He had a standard buffer, and we were using the Gemtech rounds, not reloads. He ended up lightening the buffer because it was doing the same as yours, just not coming back enough when fired. Removed one of the three weights in the buffer and it now runs. I run a standard in my SBR, but it runs fine.

TIMC,

I have a buddy that went with an already assembled 16" upper in 300BLK. It had a carbine gas system and even with an adjustable gas block added, we had to reduce weight in the buffer to get it to cycle sub sonic rounds, even with the can. Did yours run right out of the box?

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No it did not but it was not the fault of the upper. I had issues with the DPMS parts kit I used, I had to replace the hammer spring and the buffer (Extra power) spring with Wolff springs, now she is 100% reliable.

Stony said:

I've played with super and sub sonic through both of my rifles and just prefer them to be on the quieter side. I use a suppressor or .223 occasionally also, and while it seems somewhat quieter it doesn't seem like much like the effort. With the .223 it seems like the actual crack of the round is downrange a little and not as close to me....maybe it's just my imagination.

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to me, a suppressed 223 sounds a whole lot like an unsuppressed 22lr, plus a little bit of gassy sound kind of like a nail gun.

Stony said:

I've been playing with a BO with a 9 12 inch barrel and YHM suppressor. I've found that hunting with this setup leads to a problem. To stay subsonic, I'm loading a 200 fmj Lapua bullet averaging right at 1,000 fps. At this speed, the bullet will punch a nice pencil sized hole through a hog without much damage. i shot 3 a few mornings ago and had to shoot them with a 9mm to finish them off as they were still on their feet.
I'm sure a lighter bullet at a highter speed would perform better with this round in a hunting situation, but there lies the problem of staying subsonic.
I kill hogs regularly with a .223 fmj, and placed in the shoulder area they are one shot propositions, but they are traveling a lot faster when they hit the animal.
I love shooting the suppressed 300 Blackout, but I think I am going to relegate it to fun shooting and forget hunting with it.

Click to expand...

I'm going to experiment with the Lee 230 grain mold and cast some from pure lead. Hopefully that long bullet will expand, fragment or at least bend on contact with tissue.

I'm trying to work up a group buy for a NOE hollow point mold for the 300 Blackout but we haven't reached critical mass just yet. A 230 grain pure lead HP at 1050 fps should be effective on deer sized game.