BRN-180 SBR

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  • Oswaldo87

    Active Member
    Feb 1, 2020
    151
    Frederick County
    Only problem I’m running into is the three devil feature problem. Folding stock, detachable magazine, and flash hider. I plan to SBR it or see if they do an immunity SBR in regards to the brace issue. Coming to 29” is a slight issue with the Brn lower. And I will probably have to pin and weld a muzzle brake on the end.
     

    IMBLITZVT

    Ultimate Member
    Apr 20, 2009
    3,799
    Catonsville, MD
    Well the wait (end of august) is over, being shipped now.

    Time to decide on sbr or pistol

    Its really pissing me off they will not make a FA bolt for this. It looks like it would be an awesome upper. However I am not buying it until I can drop it on my registered lower. They keep advertising it and new stuff for it and its never the FA bolt... I will keep bugging them... but...
     

    Bboarder

    Me Myself & I
    Mar 7, 2010
    1,200
    Reisterstown
    Its really pissing me off they will not make a FA bolt for this. It looks like it would be an awesome upper. However I am not buying it until I can drop it on my registered lower. They keep advertising it and new stuff for it and its never the FA bolt... I will keep bugging them... but...

    I'm no machinist, but if you have a registers FA lower, how come you couldn't get a bolt machined to do the trick?
     

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,644
    MoCo
    I'm no machinist, but if you have a registers FA lower, how come you couldn't get a bolt machined to do the trick?
    Because it's not the bolt. It needs a lever. The bolt isn't long enough to trip a normal AR15 autosear. Remember, nothing goes into the buffer tube, so the bolt is short and way up near the barrel. An AR15 autosear is way in the back near the buffer tube. The Sig MCX has the same 'problem' and there is a little lever thing that can be bought to connect the bolt to the sear (I think some minor machining is still required to the upper). The BRN would need a similar solution.
     

    Bboarder

    Me Myself & I
    Mar 7, 2010
    1,200
    Reisterstown
    Because it's not the bolt. It needs a lever. The bolt isn't long enough to trip a normal AR15 autosear. Remember, nothing goes into the buffer tube, so the bolt is short and way up near the barrel. An AR15 autosear is way in the back near the buffer tube. The Sig MCX has the same 'problem' and there is a little lever thing that can be bought to connect the bolt to the sear (I think some minor machining is still required to the upper). The BRN would need a similar solution.

    Ahh, see I said I had no clue, and I was right. Lol

    I do appreciate the explanation though, it makes sense, I've never handled a FA AR or brn so like the weather man and fauci Ive been guessing.
     

    outobie

    Active Member
    Mar 7, 2012
    142
    Annapolis
    bringing this thread back for a new question. I've got my BRN 180S 300BLK on my pistol lower with a folding sig brace. it's awesom!!! now I want to look into SBRing it. what is the best approach for choosing a lower to SBR? the options as I see it are

    1 - SBR a current AR Rifle Lower (post 2013)
    2 - SBR a current AR Other/pistol lower (post 2013)
    3 - Purchase a new lower to SBR
    4 - something else?

    as a follow up question; if I SBR an existing lower (option 1 or 2) what do I do with the lower while waiting for the paperwork to go through? can I keep and use it in it's existing configuration or do I need to have an FFL hold it?...something else?
     

    Oswaldo87

    Active Member
    Feb 1, 2020
    151
    Frederick County
    I’d use whatever lower you have sitting around. Kind of up to you in a way. And you can keep the lower/firearm with you as long as it is in a legal configuration. If it makes you nervous and think Mr. ATF is going to come knocking, separate the pieces and and have a friend hold on the extra upper.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    Mine is going on a Pre-13 SBR. I put a suppressor Mount on it. I just ordered a Lage folding stock for it, which will hopefully be in this week. Here it is so far. Picatinny stock mount will take MPX stocks.
     

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    Bboarder

    Me Myself & I
    Mar 7, 2010
    1,200
    Reisterstown
    Mine is going on a Pre-13 SBR. I put a suppressor Mount on it. I just ordered a Lage folding stock for it, which will hopefully be in this week. Here it is so far. Picatinny stock mount will take MPX stocks.

    The lage 1913? That's what's on my mac11 and I want to do the same to the brn. Post photos when you get it

    What length is your upper?
     

    jcutonilli

    Ultimate Member
    Mar 28, 2013
    2,474
    Because it's not the bolt. It needs a lever. The bolt isn't long enough to trip a normal AR15 autosear. Remember, nothing goes into the buffer tube, so the bolt is short and way up near the barrel. An AR15 autosear is way in the back near the buffer tube. The Sig MCX has the same 'problem' and there is a little lever thing that can be bought to connect the bolt to the sear (I think some minor machining is still required to the upper). The BRN would need a similar solution.

    Technically the autosears are in approximately the same place. In the AR15 it is part of the lower, while in an AR18 the autosear is part of the upper. There is no way Brownells would manufacture an upper like that because it may be considered a machine gun because of the presence of the autosear. Even making it compatible is dicey. Just look how almost everyone that make AR15 bolt carriers make them incompatible with full auto rifles.
     

    smdub

    Ultimate Member
    MDS Supporter
    Nov 14, 2012
    4,644
    MoCo
    Yes, they are technically sorta in the same place. But an AR18 autosear won't work w/ an AR15 FCG. The long trip rod of the AR18 sear asembly is the magic part that is needed to connect the forward mounted short bolt to the rearward FCG. This is the pic of the AR18 sear (and the 'ears' on the upper that hold it.) for those not familiar. The rear of the sear should be swiveled down (vs up in the pic.)
    I have already discussed what it will take to trip an AR15 autosear via a short bolt. It takes an extension rod like the CMMG 22 and Sig MCX adapters. The BRN180 function really isn't all that different.

    FWIW, All my bolt carriers are FA capable. It's odd to find one that's semi auto anymore. People gave up making parts different long ago. Even some lowers are milled to the full width.
     

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