supressed SBR questions...

This is a discussion on supressed SBR questions... within the Defensive Rifles & Shotgun Discussion forums, part of the Related Topics category; I've been looking seriously looking at my next AR project. I've decided on a 11.5 inch upper that I plan to run with a suppressor ...

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    supressed SBR questions...

    I've been looking seriously looking at my next AR project. I've decided on a 11.5 inch upper that I plan to run with a suppressor (as time and cash permit).

    So my question is this:

    Looking forward and not wanting to make any mistakes, should I plan on a DI or a piston SBR upper. I've heard that suppressed SBRs can be finicky and I want to avoid making a costly mistake.

    My plan is to buy a 11.5 inch BCM DI upper but wanted to run it buy y'all before laying down the money.
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    Senior Member Array munch520's Avatar
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    DI. Any gun can be finicky. It's no wonder we're seeing a lot of it lately, what with all the inbreeding we've seen in the AR world. Pistons don't fix out of spec crap.

    An SBR from a good manufacturer (like BCM) is a great way to go, as is the 11.5" barrel. If one length has a propensity to be a pain, it's 10.3" and under.

    How often do you plan to run it with the can on? I've tailored mine for suppressed use but it'll still function unsuppressed.

    ETA:
    What can are you considering?
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    Distinguished Member Array Jaeger's Avatar
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    You could get a thousand different opinions from that question.

    There are pluses and minuses for both.

    I would decide on the suppressor first by reading what the Mfg. and range heads say about it, and comparing prices (maybe not a concern since your -$400 before you even have a part). Then I'd pick the best platform for it based on that decision (with particular attention to what the Mfg. says).

    You are obviously building it, so go on one of the AR forums and prepare to be bombarded with opinions and answers, but I would trust what the can Mfgs. say about their own products, which they want to work well, and will claim you didn't do it like they said to if you have a problem with finickyness...
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    Senior Member Array munch520's Avatar
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    Both Surefire and AAC recommend 10" barrel or longer for 5.56.
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    Quote Originally Posted by munch520 View Post
    How often do you plan to run it with the can on? I've tailored mine for suppressed use but it'll still function unsuppressed.

    ETA:
    What can are you considering?
    I would run the gun with the can on quite a bit I suppose. I have no idea what can at this point. I'm open to suggestions.

    http://www.bravocompanyusa.com/BCM-1...bfh%20lt10.htm

    ^^^^^ This is what I'm looking at right now.

    ETA: I think I'll have the SBR for a year or so before I get the can. Once I have it I'll run it most of the time I'd guess.
    Mark Twain:
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    patriot and who isn't. Its function is to obey orders, not originate them.

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    Distinguished Member Array onacoma's Avatar
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    Some piston manufacturers make a upper designed for suppression, i.e., My LWRCI M6A3 has an adjustment knob on the front of the piston and I don't think you can get that with a DI. Again check with the manufacturer, but I"m a piston person with a fetish for the 6.8mm. Here is LWRCI's upper in 5.56mm: LWRC International LLC - 5.56 PSD Upper They do work well with a muffler.


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    Senior Member Array munch520's Avatar
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    Quote Originally Posted by atctimmy View Post
    I would run the gun with the can on quite a bit I suppose. I have no idea what can at this point. I'm open to suggestions.

    http://www.bravocompanyusa.com/BCM-1...bfh%20lt10.htm

    ^^^^^ This is what I'm looking at right now.

    ETA: I think I'll have the SBR for a year or so before I get the can. Once I have it I'll run it most of the time I'd guess.
    I would suggest:

    --
    BCM 11.5" URG
    Centurion, LaRue, DD rail - 10" is good and will offer enough clearance. The 10.75" URXii will require a spacer. LaRues 11" rail is not possible.
    BCM Bolt
    LMT enhanced carrier
    BCM Gunfighter CH
    H3 buffer
    Springco blue spring

    Surefire SOCOM 7.62 mini
    Surefire muzzle device
    --

    That buffer will be a great counter to the increased backpressure. The LMT enhanced carrier has more vent holes and a wider channel for the cam pin, allowing excess backpressure to be 'bled' off. This, combined with the contour of the Gunfighter CH, should make for minimal blowback. Either way, if you like your gun clean, suppressors aren't for you If you're a lefty, you're screwed...the ejection port will spit in your face all day. Keep in mind that things get hot when suppressed, so rail/handguard choice is important, as is what you use to protect your hands (gloves, rail panels, etc).

    The two main players in the suppressor world, for ARs, are Surefire and Advanced Armament (AAC). AAC is a bit less expensive, but has some mounting issues and a bit more shift than Surefire. When I bought my SF can, I was considering it or the AAC M42000. The 556-212 was $1,046 and the M42K was $890. So ~$150 difference. Not much compared to the overall price. Both companies offer good, albeit expensive, mounts.

    I went with Surefire because it was an inch shorter, lighter, and I liked the mounting system better. I feel like the weight is perfect with the can on, but would definitely regret throwing anything bigger on there. It's a balancing act of weight, length, handling, suppression, etc.

    FWIW, Surefire has had mil contracts forever, most notably of which is the new SOCOM series (aptly named). But AAC does have some cans in service with the SEALs.

    ETA:

    You can further tailor the setup if you want with a SYRAC gas block. I see little reason for these things however, as my gun is suppressed virtually all the time. I didn't pay all that money to shoot loud...and I won't be switching back and forth between suppressed and unsuppressed enough to need a variable gas system. That said, when I am moving the can from gun to gun, I really appreciate the simplicity of the Surefire mounts and collar - especially when the shift is minimal and repeatable.
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    Senior Member Array munch520's Avatar
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    Quote Originally Posted by onacoma View Post
    Some piston manufacturers make a upper designed for suppression, i.e., My LWRCI M6A3 has an adjustment knob on the front of the piston and I don't think you can get that with a DI. Again check with the manufacturer, but I"m a piston person with a fetish for the 6.8mm. Here is LWRCI's upper in 5.56mm: LWRC International LLC - 5.56 PSD Upper They do work well with a muffler.
    PSD upper would be a no-go, as it would void most (suppressor) manufacturer's warranties
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    Senior Member Array munch520's Avatar
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    On the rail/can topic, a good rule of thumb is 1-1.5" variance between rail length and barrel length. Keep in mind that the muzzle device threads onto the barrel .7", so that 1.5" variance becomes .8-.9" when the muzzle device is installed.

    You can make it work with less (MK18 - 9.55" rail and 10.3" barrel) (11.5" upper with 10.75" rail), but you'll need a muzzle device with integral spacer to make that happen. Pics of 11.5" upper below with 10.75" rail - see how the barrel shoulder really measures at about 10.75"? The 212A flash hider moves the mounting point .25" forward to help with clearance.

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    VIP Member Array ghost tracker's Avatar
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    IMHO, if you're going that route, take a good look at chambering it in .300 Blackout! I've fallen-in with a bunch of Blackout enthusiasts and my suppressed SBR in currently in process. No need for piston drive, DI runs like a champ.
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    Can you register a currently owned lower as an SBR or do you have to purchase new and register at the same time?

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    Senior Member Array munch520's Avatar
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    You can do either
    Monotony is the awful reward for the careful

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    Munch can you elaborate on which type of rails will work better with with suppressors as far as heat dissipation goes? the SBR I am planning will have a Noveske NSR rail. If I go the suppressor route it will mainly be for HD so for the range I will probably shoot with with the can off more often. I am looking at the surefire socom series suppressor with the flash hider mount.

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    Distinguished Member Array onacoma's Avatar
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    Quote Originally Posted by munch520 View Post
    PSD upper would be a no-go, as it would void most (suppressor) manufacturer's warranties
    Please enlighten me and the other mass as to how it would void the warranty?


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    Senior Member Array munch520's Avatar
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    supressed SBR questions...

    Quote Originally Posted by onacoma View Post
    Please enlighten me and the other mass as to how it would void the warranty?
    Mike Mers (AAC) and Garin Lee (Surefire) have explicitly told me that their suppressors are not warrantied on barrels under 10" due to bullet stabilization issues inherent with 5.56/.223. PM me if you want their contact info and want to speak with them directly regarding warranties.

    I'm sure you realize that the SBR you linked to has a 8.5" barrel.
    Monotony is the awful reward for the careful

    How can man die better than facing fearful odds, for the ashes of his fathers and the temples of his Gods?

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