Dedicated Suppressed SBR *Does not function: Update Page 4*

AR/M4 Custom Build Forum
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Update 07/10/11

Update 05/10/11

Got my Rail system in today

I plan on covering the rails with index clips, and getting a Surefire M300 as well as front and rear BUIS’s within the week.

Next up will be my Aimpoint T1 and then hopefully the Forms 1 and 4 will be in.

Daniel Defense barrel with .062" gas port cut to 10.3"
AAC Brake
Shaved FSP
Noveske Upper Receiver

I have a BCM Gunfighter CH and Centurion Arms 9" rail on the way. The upper should be fully assembled and functional by Friday.

The ACOG is on it for now because its the only spare optic I have. Within a few weeks it will be wearing a T1 with Troy F/R BUIS’s, and I’ll have a Surefire M300 up front. After that all I will be waiting on will be the M4-2000.

The lower has an MOE stock and MOE grip.

It appears I will have a gap of around 0.25 inches between the end of the rail and the beginning of the suppressor, which is about as perfect as I could get it.

I am curious to see if it will function unsuppressed. I have an H and H2 buffer and some PMC Bronze and PMC X-tac with which to test it.

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I will be surprised if it runs without the suppressor. 0.062 is to small for a 10" barrel.

3

LMT’s gas ports are only .009" bigger on their 10.5s.

I won’t lose sleep over it if not, but it’ll be interesting if it does.

4

Should be fun!

Already have the suppressor or waiting on ATF?

make sure to update this weekend.

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Definitely would like to see a range report showing whether or not the bolt locks back on the last round with various types of ammo…also how soft shooting it is and how much gas blowback is mitigated. Have you considered using the LMT Enhanced BC as well?

6

I’m getting ready to dive into a similar build. Any reason you wouldn’t use a switchblock & have the best of both worlds? That’s not a facetious question either, I’m genuinely curious so I know what direction to take with mine.

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Have you ever heard a 10.3" barrel with a muzzle brake? I have no desire to shoot that short of an SBR with a brake unsuppressed. While a switchblock would have been possible on this build, I could not justify the $200 cost of the SB and pinning job when it would sit in the suppressed setting all the time. I would also be sacrificing having a full length rail.

I have plans to get a switchblock for my 14.5" Midlength, I think it is a great piece and is crucial in order to have a rifle that can fire both unsuppressed and suppressed optimally but there is no point in getting one if you won’t use it.

For me, its easy. If I want to shoot an unsuppressed SBR I will shoot my BCM 11.5".

Anything is possible in the future but as for right now I have no plans to get an enhanced carrier. I didn’t build this to spend money tweaking it to get it to function unsuppressed, and I see no reason why it will have any issues with a standard M16 carrier suppressed.

Fedex still hasn’t updated the tracking info for my shipment, its been pending a shipping label since yesterday. I’m hoping it comes in by Friday but it doesn’t look like my rail has even left the dealer yet.

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Waiting on ATF. Its been pending for 4 months. :rolleyes:

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Gotcha, I just didn’t know what your plans were since that idea has been thrown around quite a bit (by others talking about the same topic). I’m all for doing it on the cheap (while maintaing quality) and doing it right the first time!

Personally, I would love to have a setup (sans switchblock) that will shoot suppressed and unsuppressed without all the gas blowback. Whether I cut down a barrel or talk with Noveske about their “special” small port gas block, we’ll see.

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Looking forward to seeing updates on this as well…I have a barrel going to Adco very soon for a similar, if not almost exact, setup.

11

300 BLK. With supersonic the cyclic rate went up a bit more than 100 rpm from unsuppressed. You will not get a 5.56 SBR to run well unsuppressed and not gas you suppressed without some adjustable gas system.

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Todd, just wondering if you have ever shot one of your 10.5" with switchblock turned to the suppressed setting without a suppressor attached? What were the results?

Spoke with Joel today, and he says the SB “suppressed” setting is about a .064 port size. From what I surmise from Grant’s thread, this port size will cycle the bolt, but may or may not lock back on the last round. Haven’t gotten a chance to test the theory (since I don’t own either the SB/barrel or suppressor), but was wondering if you have?

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Kinda shitty, Fedex is bass ackwards and now its saying I won’t get my package until Wednesday of next week.

In any case, I can use a charging handle from another AR and fire it without the rail this weekend.

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Don’t know about that ammo, but assuming you use some 5.56, the upper will run, but might not lock back (which really isn’t that important).

IMHO, if the bolt locks back, you have to much gas (assuming you are after a semi-dedicated suppressed weapon).

C4

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Shoot! My 14.5 carbine gas system barrel almost never gasses me out. I never even think about it. I run it 80% unsupressed.

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Short stroke. Depending on the ammo and buffer it might eject.

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XTAC is supposedly equivalent to M855, however I would like to use some 5.56 Federal M193 to be sure I am using what is arguably one of the hottest commercially available 5.56 loads.

Thats good to know about the bolt locking back. Once I get everything put together I will test both with and without the can, many different types of ammo and buffer combinations.

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I have something very similar. It will NOT run with anything unsuppressed. It’s overgassed with an A5 buffer and a Ranger 2. I need to order a heavier buffer.

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What does “very similar” mean?

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Can’t be that similar…I wouldn’t call a .062 gas port ‘overgassed’