Best 300 Blackout SBR?

M1911

M1911

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So I’m daydreaming about getting a 300 Blackout SBR, once my bank account recovers from the move. My goal would be to suppress it and run subsonic. But it isn’t clear to be what would be the best gun for this. SIG has some short MCX models, but while they are piston guns it seems to me that their gas handling is bad. Any video I watch they seem to dump a lot of gas in the shooters face.

A lot of folks seem to like Q, but that is a DI gun and gassy.

Primary Weapons seems to build some piston uppers in 300 Blackout, but I’m not eager to try to build an AR for the first time.

Your thoughts?
 
i am - temporarily - a fan of cmmg dissents, and if you want a 300blk with no buffer and piston - it is a simplest option to get. and will work on plastic lowers as well.
1736216402561.png

need to get a 1 or 2 more, to play with them enough, and then go back to normal guns. :) right now all i got is a 9mm one, and it is quite a nice toy, also in 10.5".
 
paul73 said:
i am - temporarily - a fan of cmmg dissents, and if you want a 300blk with no buffer and piston - it is a simplest option to get. and will work on plastic lowers as well.
View attachment 952011

need to get a 1 or 2 more, to play with them enough, and then go back to normal guns. :) right now all i got is a 9mm one, and it is quite a nice toy, also in 10.5".
Click to expand...


This is a good choice

There's a daniel defense 300 upper that's real nice, super light and points well.
 
Caveman said:
BCM 8” currently for me. Also have a brn180sh 10” I have to build. CMMG would be on my short list.
Click to expand...
BCM would be DI, correct?

The BRN has the charging handle on the right side, which I don’t care for. As a righty, if it has a side charging handle then I want it on the left side.
 
I have an MCX SBR with a few 300blk set ups. It's neat to be able to tuck the can and change the configuration, but if I didn't get the gun for a really good deal, I would have just built a DI 9" upper.
 
M1911 said:
BCM would be DI, correct?

The BRN has the charging handle on the right side, which I don’t care for. As a righty, if it has a side charging handle then I want it on the left side.
Click to expand...
Yes DI for the BCM. Pairs well with a Nomad. The 180SH I got to experiment with especially on the manual action mode. I wanted to see how quiet I could get it. Still haven’t put it together yet though. Everyone that tries it, loves my bcm rig.
 
The first question is what is your use case and what type of ammo are you looking to shoot? Supers, subs, or both?

Honestly I think pistons are overhyped in terms of keeping gas out of your face. I know you’re not itching to build one, but a DI gun with a bleed off gas block is a great option for a suppressed 300 SBR. Standard carbine lower is fine. You just need to build the upper.
 
I shot a suppressed mcx this past week, 16” 556. Woah nelly so much gas it was miserable, given it wasn’t a low back pressure can but mine isn’t and I got waaay less gas in the face on my 12.5” BCM DI upper. And 12.5 is not known for being the best to suppress.
 
LakeTrout said:
The first question is what is your use case and what type of ammo are you looking to shoot? Supers, subs, or both?

Honestly I think pistons are overhyped in terms of keeping gas out of your face. I know you’re not itching to build one, but a DI gun with a bleed off gas block is a great option for a suppressed 300 SBR. Standard carbine lower is fine. You just need to build the upper.
Click to expand...
Subs suppressed. Basically something that could be a range toy and a home defense gun.

Every video I’ve seen of the MCX suppressed shows a ton of gas coming out the ejection port. I’d rather breathe as little of that crap as possible.
 
APFSDS said:
I shot a suppressed mcx this past week, 16” 556. Woah nelly so much gas it was miserable, given it wasn’t a low back pressure can but mine isn’t and I got waaay less gas in the face on my 12.5” BCM DI upper. And 12.5 is not known for being the best to suppress.
Click to expand...
That’s what I’ve read about the MCX, that it is really bad at handling gas.
 
From what I've heard, the newer flow through cans reduce the gasses to your face issue better than a piston upper does. IF you can afford one that is (over a grand for the can). Mostly due to most of the gas coming out of the barrel, not the gas tube. You might be able to reduce the gas from the barrel by tuning the gun (adjustable gas block and buffer combo) to reduce it in either case.

As for your question about what lower to run it on. Just get a good one (metal, not polymer) and don't worry.

You could also build it as a pistol first, before going the SBR route. Since you're in NH now. ;)
 
M1911 said:
So what sort of lower would you put that on?
Click to expand...
dissent does not care, as it is not using buffer tube. any lower will work. on metal lowers by design you will need to replace a buffer tube with a plug.
barrel wise i would not go shorter than 9. that is why 10.5" dissent upper is nice.
if you get a pistol - not sure why to sbr it, ever. you can just run it with a brace.
 
You do want a folding stock, don't you?
This was before I added the suppressor, makes a pleasant THUMP sound now.
1736220388842.png
It's a BRN180 upper on an Aero Precision AR15 lower with pic stock adapter, and a Sig folder.
Still runs flawlessly, I could probably turn down the gas when running suppressed, but I do like that I can go back and forth without making changes.
And maybe I just got lucky but the fit of the BRN180 on the Aero lower is great (but it is one of three with that combination, different calipers, and they all are great).

willing to let try it out
 
M1911 said:
Subs suppressed. Basically something that could be a range toy and a home defense gun.

Every video I’ve seen of the MCX suppressed shows a ton of gas coming out the ejection port. I’d rather breathe as little of that crap as possible.
Click to expand...
Ya I keep hearing the same thing about the MCX.

It’s not the easiest to find an upper with an easily adjustable gas block for what you’re looking for. But if you ever rethink the build option, you could get something really nice with a DI and bleed off AGB. 300 blackout subs run real nice and quiet like that. I really think that’s the best way to go for sound suppression and gas mitigation. At the very minimum I wouldn’t lock myself into piston setups.

You’ll hear all about how it mitigates gas to the face because the piston is out in the hand guard somewhere. But when you’re shooting suppressed I think most of that gas back into your face comes from the barrel not the gas tube. It’s just not in my experience that piston guns send less back as a rule. And I think that explains why.
 
M1911 said:
So I’m daydreaming about getting a 300 Blackout SBR, once my bank account recovers from the move. My goal would be to suppress it and run subsonic. But it isn’t clear to be what would be the best gun for this. SIG has some short MCX models, but while they are piston guns it seems to me that their gas handling is bad. Any video I watch they seem to dump a lot of gas in the shooters face.

A lot of folks seem to like Q, but that is a DI gun and gassy.

Primary Weapons seems to build some piston uppers in 300 Blackout, but I’m not eager to try to build an AR for the first time.

Your thoughts?
Click to expand...

As much of a tool Kevin Brittingham is, I have to say that probably the best 300 BLK gun is the Honey Badger SD. For the following reasons;

AAC (founded by Brittingham) engineered and brought 300BLK to market as well as the gen 1 Honey Badger for SOCOM for their LVAW program to replace their MP5s with a low visibility rifle cartridge PDW-type weapon for CQC.

The gen 2 Honey Badger at Q was entirely engineered in house as a complete weapon system. The HB is engineered around 300 BLK, not taking an AR and adopting the round. The Honey Badger SD also comes with a Q suppressor specifically engineered for the system and only available with the Badger, not sold standalone. Even with the can, the HoneyBadger SD weighs in at like 5.5 lbs. It’s stupid light.

All that said, the MCX is excellent but heavy for what it is. The MCX LT Spear Rattler is tempting. I built an LMT with a 9 inch barrel, a Noveske with an under 8 inch barrel and run a DDM4 300S with a 10.4 inch barrel all in 300 BLK. I also built an HK416 clone in 300 BLK with an 11” barrel and took some fine tuning to run right but now reliably runs subs. It’s also a little heavy but has zero recoil and locks back every time on last round.

Another excellent contender that came out a couple months ago is the FN SCAR 15P. The one below is identical to mine but I am still waiting on my tax stamp for my form1. I have a brace on mine at the moment but is light, has an adjustable gas block, has a 7.5” barrel, and runs 300 BLK subs very reliably with low recoil.

You’re welcome to shoot any/all of these if you want to meet me at Chester R&G.

IMG_0776.jpeg

IMG_0314.jpeg
IMG_0892.webp

IMG_0125.jpeg

IMG_0890.jpeg
 
Last edited:
Tartakovsky said:
As much of a tool Kevin Brittingham is, I have to say that probably the best 300 BLK gun is the Honey Badger SD. For the following reasons;

AAC (founded by Brittingham) engineered and brought 300BLK to market as well as the gen 1 Honey Badger for SOCOM for their LVAW program to replace their MP5s with a low visibility rifle cartridge PDW-type weapon for CQC.

The gen 2 Honey Badger at Q was entirely engineered in house as a complete weapon system. The HB is engineered around 300 BLK, not taking an AR and adopting the round. The Honey Badger SD also comes with a Q suppressor specifically engineered for the system and only available with the Badger, not sold standalone. Even with the can, the HoneyBadger SD weighs in at like 5.5 lbs. It’s stupid light.

All that said, the MCX is excellent but heavy for what it is. The MCX LT Spear Rattler is tempting. I built an LMT with a 9 inch barrel, a Noveske with an under 8 inch barrel and run a DDM4 300S with a 10.4 inch barrel all in 300 BLK. I also built an HK416 clone in 300 BLK with an 11” barrel and took some fine tuning to run right but now reliably runs subs. It’s also a little heavy but has zero recoil and locks back every time on last round.

Another excellent contender that came out a couple months ago is the FN SCAR 15P. The one below is identical to mine but I am still waiting on my tax stamp for my form1. I have a brace on mine at the moment but is light, has an adjustable gas block, has a 7.5” barrel, and runs 300 BLK subs very reliably with low recoil.

You’re welcome to shoot any/all of these if you want to meet me at Chester R&G.

View attachment 952031

View attachment 952032
View attachment 952035

View attachment 952034

View attachment 952033
Click to expand...

I think that Noveske is the prettiest.
 
paul73 said:
i am - temporarily - a fan of cmmg dissents, and if you want a 300blk with no buffer and piston - it is a simplest option to get. and will work on plastic lowers as well.
View attachment 952011

need to get a 1 or 2 more, to play with them enough, and then go back to normal guns. :) right now all i got is a 9mm one, and it is quite a nice toy, also in 10.5".
Click to expand...
CummingsFamilyFirearms is right in Atkinson NH. Just wanted to let you guy know in case you guys are local to here.
 

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