New ar15 SBR to be run 90% of the time suppressed

jkhoopster · November 19, 2017, 05:10 PM

Hello all!

I am a long time lurker here and I wanted to get some opinions on a build I am doing for an SBR that will be run 90% of the time suppressed. I am wanting something pretty high end and am willing to put 1500 into this build before optics and trigger (i already have those). I am prioritizing light weight in most of my parts as well. This will mostly be used for a range plinker and home defense gun.

Also I am leaning toward an Sico Omega 30 cal can at this moment. If anyone has any experience with 30 cal cans please chime in with that as well.

The build:

Barrel: Triarc 11.5 inch TRACK 2.0 Barrel.
https://www.triarcsystems.com/rifles...l#.WhH_fkqnGUk

Upper: Aero stripped upper w/ NO Forward Assist

Port Door: Strike Industries Ultimate

Handguard: Midwest Industries G3 Lightweight LWM-Series One Piece Free Float Handguard, M-LOK in the 10 inch variety

Gas block: Superlative Arms .750 Adjustable gas block (anyone have any thoughts on clamp on vs one piece?)

Bolt Carrier: LMT Enhanced Bolt carrier

Gas tube: Carbine length gas tube

Charging handle: Griffin Armament SNACH (open to other options on vented/gas relief charging handles)

Muzzle Device: whichever suppressor I get QD mount

Lower Receiver: Aero Stripped lower

LPK: Ambi lower parts kit

Trigger: Geissle SSA trigger

Buffer kit: BCM A5 kit

2damnold4this · November 19, 2017, 06:12 PM

I'm not an AR guru so I don't have a comment but I do have a question: Why 5.56 over 300blk for a suppressed SBR?

And welcome to TFL!

jkhoopster · November 19, 2017, 06:20 PM

I am not really excited to get into a new caliber right now. Plus I can shoot 5.56 for way cheaper. I reload it and have all components already laying around. I definitely see a 300 blackout SBR in my future but it will be a ways down the road.

Sharkbite · November 19, 2017, 06:53 PM

I have a few SBR’s, one is a 10.5” 556 that i run exclusively with a 30 cal can.

While i understand your point about shooting 556 cheaper...the 556 loses so much out of the shorter barrels, my go to SD/HD SBR is a 300blk (also suppressed).

That said, here are my thoughts on A 556 SBR with a 30cal can.... the can will be bigger and heavier then you need. The increased volume is negated by the larger exit hole. So, its about the same noise reduction as a true 556 can.

The advantage (and why i do it) is the ability to cross deck it onto other platforms. If you like the versatility that offers, then a 30cal can makes sense. If not get a true 556 can and save the weight.

The velocity lose from the short barrel “can” be overcome to some extant by using speciality ammo. A standard 62gn fmj SUCKS at that barrel length for anything serious. Fine for punching paper or ringing steel.

For SD/HD you are going to need to drop some coin on premium ammo. My preference is Hornady TAP

With the budger you have in mind...maybe SBR 1 lower and build 2 uppers. One in 556, one in 300blk

Bartholomew Roberts · November 19, 2017, 06:59 PM

Well, if you are specifying your port door, you are likely already interested in small details; but I will say I've got .300 BLK and 5.56 suppressors and ARs, and I'ved used various charging handles designed to reduce gas to the face. Putting sealant around the charging handle works best, but none of them do much as most of the backpressure is coming through the ejection port.

The main thing the "Enhanced LMT Carrier" does is deal with extra gas pressure caused by suppressed, short barrelled 5.56 rifles by venting it faster with three holes instead of two. I think it is redundant and unnecessary if you already have an adjustable gas port and you can enhance yourself right into poor function using that carrier outside of the specific parameters you have in mind.

Between the adjustable gas, A5 buffer, suppressor, and Enhanced LMT carrier, if you do have a function problem, it will be a pain to diagnose and the knowledge base of people with those parts who can offer advice will be really small.

jkhoopster · November 19, 2017, 08:11 PM

I do plan to just get a 300 blackout upper when I do decide to get into that caliber.

I should also mention I have a 308 ar10 that I want to suppress so that is a big reason why for the 30 cal can plus the 300 blackout down the road.

I am somewhat concerned about what Bartholomew Roberts posted. My thinking with the LMT enhanced carrier and adjustable gas block is even if I have a problem, I can just adjust problems away by increasing or decreasing gas. I have talked to a few other folks who have used adjustable gas blocks and the LMT carrier and they have not had issues. Apparently the first few generations of the LMT carrier were not designed with sbr's in mind. I have read LMT has made some changes to allow it to function in SBR's.

Also after posting this I am considering changing out the BCM a5 kit for Vltor a5 kit since it comes with an h2 buffer instead of an h0 buffer like the BCM kit. Any thoughts on the buffer strength?

Coloradohtr · November 19, 2017, 11:21 PM

Sounds like a good build to me. I'm working on one myself. Currently set up as a pistol though.

Mine is built on an Anderson lower with a standard milspec trigger for now, a Hogue pistol grip and a Thordsen Customs buffer tube kit, Magpul B.A.D lever and extended magazine release.

The upper is a 8 1/2" barrel chambered in 300blk with a Strike Industries cookie cutter break. It has an Aero Precision bolt and extended ambi charging handle. Handguard is a Trinity Force 8" M-Loc with a Magpul angled forgrip and 2" rails on each side. Sights are Magpul MBUS pro front and rear and I'm currently running a Vortex Venom red dot until I can get an EOtech or a Vortex Sparc or something similar. I like it. It's pretty handy. Haven't decided on the suppressor yet but I'll find one soon.

Bartholomew Roberts · November 20, 2017, 08:04 AM

The LMT Enhanced carrier was originally made to help function in suppressed 10.5” and 10.3” Mk18 ARs. This was prior to common use of adjustable gas blocks. The problem was that with the additional dwell time and backpressure, SBRs with big gas ports designed around short dwell times were overgassed when you added a suppressor (which was further complicated by heat and gas port erosion on the shooting schedules those rifles were subjected to). The third hole helps gas vent faster once the gas rings on the bolt are pushed past that point. Function issues happened when people thought “O wow! That’s what the military uses in the Mk18? I’ll put that in my 20” rifle and ‘enhance’ my reliability even more.”

You don’t really need the third vent because you can control gas flow at the port. Is there some other feature the LMT Enhanced carrier offers that you really wanted? ETA: The carrier looks to be about 20% of your overall rifle budget. Is the longer track for the cam pin worth that to you?

As for all the parts, that configuration may work just fine. If it doesn’t though, trying to figure out whether it is the different buffer, different spring, carrier, adjustable gas port, etc. is going to be tough unless you have an already functional 11.5” SBR with the same gear you can compare it to. That’s all I was trying to say there.

Mobuck · November 20, 2017, 08:17 AM

You probably won't like this but: You won't be as happy with a short barrel and a .30 can as you might hope. The choice of a "bleed off" gas block somewhat negates the expectation of quiet. You're putting more concern into gas blow back than the actual problem exhibits.
Since you specify the need for a QD mount, give this some thought. A 14.5" barrel with a pinned QD mount/flash hider is 16" making it legal to travel with and possess in places where the SBR is a no-no. A can suitable for such short barrel use is going to be heavier and/or more expensive than one rated for a longer barrel. A more compact can on a slightly longer barrel ends up with the same overall length.
I used a .30 cal can on a .223 for a couple of years before getting a dedicated .223 can AND LEARNING WHAT GOOD SUPPRESSION SOUNDS LIKE.

November 19, 2017, 05:10 PM	#1
jkhoopster Junior Member Join Date: November 18, 2017 Posts: 3	New ar15 SBR to be run 90% of the time suppressed Hello all! I am a long time lurker here and I wanted to get some opinions on a build I am doing for an SBR that will be run 90% of the time suppressed. I am wanting something pretty high end and am willing to put 1500 into this build before optics and trigger (i already have those). I am prioritizing light weight in most of my parts as well. This will mostly be used for a range plinker and home defense gun. Also I am leaning toward an Sico Omega 30 cal can at this moment. If anyone has any experience with 30 cal cans please chime in with that as well. The build: Barrel: Triarc 11.5 inch TRACK 2.0 Barrel. https://www.triarcsystems.com/rifles...l#.WhH_fkqnGUk Upper: Aero stripped upper w/ NO Forward Assist Port Door: Strike Industries Ultimate Handguard: Midwest Industries G3 Lightweight LWM-Series One Piece Free Float Handguard, M-LOK in the 10 inch variety Gas block: Superlative Arms .750 Adjustable gas block (anyone have any thoughts on clamp on vs one piece?) Bolt Carrier: LMT Enhanced Bolt carrier Gas tube: Carbine length gas tube Charging handle: Griffin Armament SNACH (open to other options on vented/gas relief charging handles) Muzzle Device: whichever suppressor I get QD mount Lower Receiver: Aero Stripped lower LPK: Ambi lower parts kit Trigger: Geissle SSA trigger Buffer kit: BCM A5 kit

November 19, 2017, 11:21 PM	#7
Coloradohtr Member Join Date: February 29, 2016 Posts: 49	Sounds like a good build to me. I'm working on one myself. Currently set up as a pistol though. Mine is built on an Anderson lower with a standard milspec trigger for now, a Hogue pistol grip and a Thordsen Customs buffer tube kit, Magpul B.A.D lever and extended magazine release. The upper is a 8 1/2" barrel chambered in 300blk with a Strike Industries cookie cutter break. It has an Aero Precision bolt and extended ambi charging handle. Handguard is a Trinity Force 8" M-Loc with a Magpul angled forgrip and 2" rails on each side. Sights are Magpul MBUS pro front and rear and I'm currently running a Vortex Venom red dot until I can get an EOtech or a Vortex Sparc or something similar. I like it. It's pretty handy. Haven't decided on the suppressor yet but I'll find one soon. Last edited by Coloradohtr; November 19, 2017 at 11:34 PM.

November 20, 2017, 08:04 AM	#8
Bartholomew Roberts member Join Date: June 12, 2000 Location: Texas and Oklahoma area Posts: 8,462	The LMT Enhanced carrier was originally made to help function in suppressed 10.5” and 10.3” Mk18 ARs. This was prior to common use of adjustable gas blocks. The problem was that with the additional dwell time and backpressure, SBRs with big gas ports designed around short dwell times were overgassed when you added a suppressor (which was further complicated by heat and gas port erosion on the shooting schedules those rifles were subjected to). The third hole helps gas vent faster once the gas rings on the bolt are pushed past that point. Function issues happened when people thought “O wow! That’s what the military uses in the Mk18? I’ll put that in my 20” rifle and ‘enhance’ my reliability even more.” You don’t really need the third vent because you can control gas flow at the port. Is there some other feature the LMT Enhanced carrier offers that you really wanted? ETA: The carrier looks to be about 20% of your overall rifle budget. Is the longer track for the cam pin worth that to you? As for all the parts, that configuration may work just fine. If it doesn’t though, trying to figure out whether it is the different buffer, different spring, carrier, adjustable gas port, etc. is going to be tough unless you have an already functional 11.5” SBR with the same gear you can compare it to. That’s all I was trying to say there. Last edited by Bartholomew Roberts; November 20, 2017 at 10:57 AM.

November 19, 2017, 06:12 PM	#2
2damnold4this Senior Member Join Date: August 12, 2009 Location: Athens, Georgia Posts: 2,526	I'm not an AR guru so I don't have a comment but I do have a question: Why 5.56 over 300blk for a suppressed SBR? And welcome to TFL!

November 19, 2017, 06:20 PM	#3
jkhoopster Junior Member Join Date: November 18, 2017 Posts: 3	I am not really excited to get into a new caliber right now. Plus I can shoot 5.56 for way cheaper. I reload it and have all components already laying around. I definitely see a 300 blackout SBR in my future but it will be a ways down the road.

November 19, 2017, 06:53 PM	#4
Sharkbite Senior Member Join Date: November 4, 2013 Location: Western slope of Colorado Posts: 3,679	I have a few SBR’s, one is a 10.5” 556 that i run exclusively with a 30 cal can. While i understand your point about shooting 556 cheaper...the 556 loses so much out of the shorter barrels, my go to SD/HD SBR is a 300blk (also suppressed). That said, here are my thoughts on A 556 SBR with a 30cal can.... the can will be bigger and heavier then you need. The increased volume is negated by the larger exit hole. So, its about the same noise reduction as a true 556 can. The advantage (and why i do it) is the ability to cross deck it onto other platforms. If you like the versatility that offers, then a 30cal can makes sense. If not get a true 556 can and save the weight. The velocity lose from the short barrel “can” be overcome to some extant by using speciality ammo. A standard 62gn fmj SUCKS at that barrel length for anything serious. Fine for punching paper or ringing steel. For SD/HD you are going to need to drop some coin on premium ammo. My preference is Hornady TAP With the budger you have in mind...maybe SBR 1 lower and build 2 uppers. One in 556, one in 300blk

November 19, 2017, 06:59 PM	#5
Bartholomew Roberts member Join Date: June 12, 2000 Location: Texas and Oklahoma area Posts: 8,462	Well, if you are specifying your port door, you are likely already interested in small details; but I will say I've got .300 BLK and 5.56 suppressors and ARs, and I'ved used various charging handles designed to reduce gas to the face. Putting sealant around the charging handle works best, but none of them do much as most of the backpressure is coming through the ejection port. The main thing the "Enhanced LMT Carrier" does is deal with extra gas pressure caused by suppressed, short barrelled 5.56 rifles by venting it faster with three holes instead of two. I think it is redundant and unnecessary if you already have an adjustable gas port and you can enhance yourself right into poor function using that carrier outside of the specific parameters you have in mind. Between the adjustable gas, A5 buffer, suppressor, and Enhanced LMT carrier, if you do have a function problem, it will be a pain to diagnose and the knowledge base of people with those parts who can offer advice will be really small.

November 19, 2017, 08:11 PM	#6
jkhoopster Junior Member Join Date: November 18, 2017 Posts: 3	I do plan to just get a 300 blackout upper when I do decide to get into that caliber. I should also mention I have a 308 ar10 that I want to suppress so that is a big reason why for the 30 cal can plus the 300 blackout down the road. I am somewhat concerned about what Bartholomew Roberts posted. My thinking with the LMT enhanced carrier and adjustable gas block is even if I have a problem, I can just adjust problems away by increasing or decreasing gas. I have talked to a few other folks who have used adjustable gas blocks and the LMT carrier and they have not had issues. Apparently the first few generations of the LMT carrier were not designed with sbr's in mind. I have read LMT has made some changes to allow it to function in SBR's. Also after posting this I am considering changing out the BCM a5 kit for Vltor a5 kit since it comes with an h2 buffer instead of an h0 buffer like the BCM kit. Any thoughts on the buffer strength?

November 20, 2017, 08:17 AM	#9
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	You probably won't like this but: You won't be as happy with a short barrel and a .30 can as you might hope. The choice of a "bleed off" gas block somewhat negates the expectation of quiet. You're putting more concern into gas blow back than the actual problem exhibits. Since you specify the need for a QD mount, give this some thought. A 14.5" barrel with a pinned QD mount/flash hider is 16" making it legal to travel with and possess in places where the SBR is a no-no. A can suitable for such short barrel use is going to be heavier and/or more expensive than one rated for a longer barrel. A more compact can on a slightly longer barrel ends up with the same overall length. I used a .30 cal can on a .223 for a couple of years before getting a dedicated .223 can AND LEARNING WHAT GOOD SUPPRESSION SOUNDS LIKE.