Thoughts on my planned 300 BLK SBR/Suppressor build

Right now I'm putting the finishing touches on my planned suppressed SBR design. I'll try and list the main preliminary options I've decided go with, along with some of the alternates I'm considering. Any and all constructive feedback is appreciated, and if you have any suggestions on changes also telling me WHY you consider that a good change would be helpful. This is primarily going to be a range gun, but it will also be my home defense gun if something goes bump in the night. Thanks, looking forward to reading the comments/criticism

Lower Receiver: PSA Stripped Lower

LPK: PSA parts kit.

Grip: BCM Gunfighter. I also like the Magpul MOE grip, so I could go with either.

Trigger: Geissele SSA. (I love my Geissele SSA-E, but I wanted something a bit heavier for HD use). I was batting around the idea of a Geissele S3G with a 4.5# spring, but as I use an SSA-E for the majority of my target shooting, I figured keeping it 2 stage would help my muscle memory.

Stock:*WAS* B5 SOPMOD Bravo. I currently have a B5 SOPMOD on my 16" rifle, and I love the cheekweld and general feel of the stock. That being said, I don't really find myself needing the battery compartments, and this will save a few dollars, and more importantly ounces (ounces lead to pounds, pounds lead to pain).

Buffer Tube: *ADD* (courtesy of advice from Clandestine): VLTOR A5 Buffer Tube.

Misc: Magpul BAD Lever: Big fan of this. I feel faster and more efficient doing mag changes and locking the bolt to the rear.

Upper Receiver:

Barrel Length: 9". I was looking at 8.2", 10.5", and 12.5", but I'm right now heavily leaning towards 9". I recall an AAC rep mentioning that was the "sweet spot", and that most of the powder burned off within the first 8 inches and change, and there was no huge advantage of going with a longer barrel.

Bolt Carrier: PSA Full Auto Nickel Boron BCG.

Charging Handle: BCM Gunfighter Mod 4.

Rail: Midwest Industries Free Float Lightweight M-LOK 9" if available. If not, some form of lightweight M-LOK handguard, ideally 9" in length.

Muzzle Device: The suppressor I go with will influence this. As right now I'm going for a SilencerCo Saker 7.62, I'd be using their Trifecta mount. My alternative choice was the Surefire SOCOM762-RC. I also looked briefly at the YHM line of both stainless and titanium.

Optic: Aimpoint PRO or Aimpoint T-1. I looked at EOTech, but at the end of the day I found myself preferring Aimpoint.

BUIS: Most likely Magpul Gen2 MBUS.

Accessories: HSP WML (200 Lumen).
Accessories: Magpul MS3 sling.

Sounds like a solid build.

Do you have the lower now?

If not your going to have to buy an AR pistol that's on the MD Roster or buy an entire HBAR AR15 to get a host receiver.

If you go with a 9" barrel the OAL wont pass ATF your Form 1 because your OAL will be shorter than 29". You can build any Post October 1, 2013 Centerfire, Semi Automatic, SBR's on a Form 1 if they are under 29". If you pin the suppressor mount that may give you 29" OAL, or youll have to choose a stock that may give you a longer length when extended.

Won't a 9" barrel be too short for MD? I'm doing one with a 10.5" barrel and OAL will be 29.75". You need to be >29"

Wow, one of those rare cases where 9" is just too short...

clandestine said:

Sounds like a solid build.

Thanks!

Do you have the lower now?

Yes I do. I made sure to grab a few before Oct 1st.

If not your going to have to buy an AR pistol that's on the MD Roster or buy an entire HBAR AR15 to get a host receiver.

If you go with a 9" barrel the OAL wont pass ATF your Form 1 because your OAL will be shorter than 29". You can build any Post October 1, 2013 Centerfire, Semi Automatic, SBR's on a Form 1 if they are under 29". If you pin the suppressor mount that may give you 29" OAL, or youll have to choose a stock that may give you a longer length when extended.

Click to expand...

Thanks for the reminder... I'm going to crunch some numbers again and double check my math. IIRC a 10.5" barrel is required to get the OAL of a standard AR to 29.5", so with a 9" barrel and the pinned Trifecta FH adding another 1.75" I thought I'd be good to go.

teratos said:

Won't a 9" barrel be too short for MD? I'm doing one with a 10.5" barrel and OAL will be 29.75". You need to be >29"

Click to expand...

I was planning on pinning a Trifecta FH to it, which adds 1.75" which should get me to where I need to be ( see above reply to Clandestine ).

I love the Sako, however. Advanced Armament's ranger is my first choice. You can purchase a flash hider from them which will add 2-3 inches of OAL. They support screw on suppressors which give you serious dynamic capability.

Also on my .300 build I went for an adjustable gas block. They allowed me to adjust my gas return to the precious amount I needed to cycle the rounds I wanted without over/under.

FYI my gun was mainly 150-200 yard super sonic hunting. Suppression of supersonic is mostly for my hearing sanity.


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You should be GTG. Solid Build!

Now get that Form 1 off and post some pics in about 9 months.

Respen33 said:

I love the Sako, however. Advanced Armament's ranger is my first choice. You can purchase a flash hider from them which will add 2-3 inches of OAL. They support screw on suppressors which give you serious dynamic capability.

Also on my .300 build I went for an adjustable gas block. They allowed me to adjust my gas return to the precious amount I needed to cycle the rounds I wanted without over/under.

FYI my gun was mainly 150-200 yard super sonic hunting. Suppression of supersonic is mostly for my hearing sanity.


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Click to expand...

Agreed on the Adjustable Gas Block. The only one I like is the newer variant of the Syrac Ordnance Low Profile GAs Block, as it has a detent adjustment that's easy to adjust and does not foul up with carbon.

A Short gun changes function a good bit when adding/removing a suppressor.

Looks like a great build. Let me know if you'd be interested in a full 9" AAC upper. I've got a brand new one that I'm trying to sell...

While I have everyone's attention, any suggestions on a new torque wrench for installing/removing barrel nuts?

You going to be building a lot of guns or is this just for occasional use? If it is occasional get a harbor freight unit.

clandestine said:

You going to be building a lot of guns or is this just for occasional use? If it is occasional get a harbor freight unit.

Click to expand...

I'd love to build a lot... but for now I just have this build planned for the near future. Eventually I'd like to build an SPR type AR-15, and I want to swap out a handguard on another rifle, but that's in the future. At the most I'd maybe need to use it 4 or 5 times over the next year.

Harbor Freight then.

Okie doke, gracias.

PS now you seriously have me thinking on going the 10.5 route so I don't have to pin the FH. Hm.

Use a Vltor A5 buffer tube and a magpul stock with enhanced pad. That will add almost 2"

clandestine said:

Use a Vltor A5 buffer tube and a magpul stock with enhanced pad. That will add almost 2"

Click to expand...

Good idea. The ACS-L looks like it'd fit flush, though as that isn't going to be a huge issue for me the CTR might also work.

FYI VLTOR is blowing out their original modstocks for $50 each.

http://www.vltorstore.com/clearance-modstock/

clandestine said:

Use a Vltor A5 buffer tube and a magpul stock with enhanced pad. That will add almost 2"

Click to expand...

Bingo!

Plan on using the 9" AAC upper with the VLTOR A5 buffer and Magpul ACS-L stock. If I did my math correctly OAL should be 29.25".

But I am an idiot. I submitted my form 1 back on 2/23 with a OAL of 27.5 after seeing some alleged MSP sign offs for less than 29". I called the ATF to ask about changing the OAL on my submission and they said I would have to cancel and resubmit.

+1 on the Adjustable gas block. I run a 8.2" Noveske with AAC 762-SDN-6 and unless you use an adjustable gas block your going to eat a lot of gas when shooting supersonic suppressed.

I chose the Micromoa adjustable gas block. You don't need any tools to adjust the gas just a bullet or finger depending on your forearm. It has detents and up to 3 positions. I set mine up to run everything suppressed. 1 position for Supersonic, Subsonic and gas off to make it as quiet as possible. Of course you then have to charge the gun after each round but it makes quite a difference.