AR Pistol build

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  • danb

    dont be a dumbass
    Feb 24, 2013
    22,704
    google is your friend, I am not.
    If you have built lowers, a pistol lower is the same. Watch out for PDW braces that require special tubes/springs.



    Some will say that the tricky part is the "piston upper." Some are reliable, some not. My AR pistol is standard "DI" and runs fine suppressed. My 0.02 - get a adjustable gas block (SLR) and call it a day. I understand why you want a piston running suppressed, but am not sure that the extra weight of a piston is worth it when you cannot be sure of the reliability.
     

    teratos

    My hair is amazing
    MDS Supporter
    Patriot Picket
    Jan 22, 2009
    59,775
    Bel Air
    If you have built lowers, a pistol lower is the same. Watch out for PDW braces that require special tubes/springs.



    Some will say that the tricky part is the "piston upper." Some are reliable, some not. My AR pistol is standard "DI" and runs fine suppressed. My 0.02 - get a adjustable gas block (SLR) and call it a day. I understand why you want a piston running suppressed, but am not sure that the extra weight of a piston is worth it when you cannot be sure of the reliability.

    Running a piston AR is a sin.

    The Book of SOTAR 1:3.
     

    danb

    dont be a dumbass
    Feb 24, 2013
    22,704
    google is your friend, I am not.
    Running a piston AR is a sin.

    The Book of SOTAR 1:3.


    I am a sinner.

    There is definitely something to be said about a gun that runs clean when suppressed.


    I'm wanting to use a piston because I've been running the Raider on my rifle for years and it's incredibly dirty. One trigger pull looks like I've fired two mags through the gun. Adams Arms makes a couple of interesting piston uppers with adjustable gas blocks all set up and ready to go. Their reviews are pretty decent too. I know a lot of traditionalists don't care for the piston system for the AR but I can see advantages and disadvantages to both. My build skill level doesn't make me comfortable with building an upper hence the one stop shop for a piston upper with BCG ready to go.


    You have not seen dirt until you've run many boxes of 9mm through a suppressed MP5. But I hear you on the dirt factor.
     

    shadow116

    2nd Class Citizen
    Feb 28, 2008
    1,542
    Emmitsburg
    You have not seen dirt until you've run many boxes of 9mm through a suppressed MP5. But I hear you on the dirt factor.

    Nothing compares to cleaning an M-60E3, after 2 weeks of running around the boonies, firing over 1K of blanks, and using enough LSA to choke a donkey.

    It puts to shame the dirt from a MP-5SD after many days at the range. I know this.
     

    SkiPatrolDude

    Ultimate Member
    MDS Supporter
    Oct 24, 2017
    3,331
    Timonium-Lutherville
    Be mindful of "LOP" from the brace not to exceed 13.5 inches. It's not written in stone but there are instances of the ATF charging individuals with possession or manufacture of an SBR because their brace exceeded 13.5 LOP, which apparently the ATF has arbitrarily used to justify it's use as a stock.

    Most brace manufacturers have taken this into account, but if you add a folding stock adapter, then you will most likely exceed 13.5 LOP. SB Tactical makes "LOP Limiters" which solve this issue. Also, do not remove or modify the brace strap - Keep the brace 100% stock on the buffer tube to avoid ever being accused of a "redesign".
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    I'm in my waiting period for an Aero M4E1 lower that I want to build into a 5.56 pistol. I will be suppressing it with my AWC Raider and I want to use a piston upper with at least a 10.5" barrel. I've built a couple rifle lowers before but this is my first pistol build. I would like to buy a complete upper after I build the lower. Any suggestions or pitfalls I should be aware of?
    Drive for show. Putt for dough.


    Building lowers is driving.


    Building uppers is putting. The money shot.


    EODJoe, I've got Adams piston kits for carbine, midlength, and rifle. They're just sitting around. I can let you have one cheap. If you're really interested, shoot me a PM.
     

    SkiPatrolDude

    Ultimate Member
    MDS Supporter
    Oct 24, 2017
    3,331
    Timonium-Lutherville
    So all my parts finally showed up and I completed this build over the weekend. Definitely happy with it so far. I need to get to the range and get it zeroed hopefully this week.

    Shes real purdy.

    I love those M4E1 lowers. I have two and they are the nicest looking lowers I have. My other two are Spikes and DD so I feel that is decent grounds for comparison. For ~$95 you'd be hard pressed to beat it.
     

    alucard0822

    For great Justice
    Oct 29, 2007
    17,643
    PA
    I am in the process of building an 80% dedicated .22 pistol. I may use the CMMG 5 inch barrel and handguard but, damn, they are expensive. Are there any cheaper options out there?
    the RTB kits, barrels and parts seem to be straight up CMMG manufactured, often for a little less https://www.righttobear.com/22LR-AR15-M4-Barrels-s/1907.htm

    as far as a handguard, you can use most anything, they have M-lok free float handguards for $65, plenty of other cheap handguards to choose from too. Not many are under 7" though, unless you plan on running a can under the handguards can probably use a random linear comp to extend the muzzle a little past the guards.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    the RTB kits, barrels and parts seem to be straight up CMMG manufactured, often for a little less https://www.righttobear.com/22LR-AR15-M4-Barrels-s/1907.htm

    as far as a handguard, you can use most anything, they have M-lok free float handguards for $65, plenty of other cheap handguards to choose from too. Not many are under 7" though, unless you plan on running a can under the handguards can probably use a random linear comp to extend the muzzle a little past the guards.
    Pardon my ignorance(or don't), is a buffer tube and spring still needed for one of those builds?
     

    alucard0822

    For great Justice
    Oct 29, 2007
    17,643
    PA
    So all my parts finally showed up and I completed this build over the weekend. Definitely happy with it so far. I need to get to the range and get it zeroed hopefully this week.

    Thats sweet, being there are effectively 0 standards for AR piston systems and they are really hit or miss, I've always done my best to work with the DI gas system. IMO the only real potential benefits of a piston AR is running suppressed, depending on where and how the gas is vented from the piston, it can be pretty pleasant and run well suppressed or open, or give a lot of bark and blast under the handguard. Have been eyeballing the PWS mk1mod2 setups, but not sure how much better it would be with tuned gas dumping under the rail vs out the ejection port and in the receiver.
     

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