First AR pistol build

First AR pistol build

This is a discussion on First AR pistol build within the Defensive Rifles & Shotgun Discussion forums, part of the Related Topics category; This last year I've missed out on more than one coyote because I need two hands to run the AR carbine. So I decided to ...

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  1. #1
    Distinguished Member Array TSKnight's Avatar
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    First AR pistol build

    This last year I've missed out on more than one coyote because I need two hands to run the AR carbine.
    So I decided to build an AR pistol.
    Primary purpose will be HD with the possibility of some varmint control.

    I've had AR's since '82, "but have not built one before.
    As this is my for time building an AR I'm looking for some advice from those who have done it before.
    Have not done much research beyond the basics.AR
    I have a complete Anderson lower less the recoil tube as a starting point.

    Some questions:
    I'm thinking short, 7-7.5" barrel in 223/556 for easy handling. Pro's and con's?

    Should I consider another caliber? I know I'm giving up quite a bit of velocity.

    Any other ideas/suggestions?
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    VIP Member Array OldChap's Avatar
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    I would not recommend anything much less than 10.5 inches for a 5.56 pistol. You get into a lot of issues, not the least of which are gas port settings, and then there are ammunition issues. The 55-62 grain 5.56 bullet is effective because it tumbles on impact. However, that tumbling is entirely dependent on velocity. At low velocities, it tends to make pinpoint wounds. Be sure you get a 1:7 twist so it will stabilize the long 75-77 grain loads.

    The 10.5 works pretty well for 5.56 regardless of gas issues and the longer and heavier 75-77 grain loadings restore a lot of what you lose in defense effectiveness. Again 1:7 twist is necessary.

    My favorite short barrel AR is an 8.5 inch 300 AAC Blackout. You get great power and effectiveness for defense, and if you decide to go with a silencer some day, the selection of very heavy bullets (same bullet as a .308) far over shadows the 5.56. That and a silenced 300 running subsonic 220 gr loads is about the same decibel level as an MP5-SD.

    The other great options for a compact defense gun are 9mm or 40S&W uppers - although you will need to run EndoMag inserts in Pmag 5.56 magazines OR a dedicated 9mm lower with Colt SMG or Glock mags. The 40 ( somebody correct me here ) requires a dedicated lower using Glock magazines. You can go all the way down to a 4 inch barrel for the 9mm. That makes for about the smallest AR on earth. At the other end of the spectrum, the 40 in a 10-16 inch barrel with a 135 grain load eclipses the power of even the .357 Magnum.

    If I could only have one, it would be the 300, although the 9mm is very nice. Why limit yourself?
    "The difference between genius and stupidity is that genius has limits."

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  3. #3
    Senior Member Array Grizzly2's Avatar
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    I've never played or even handled an AR pistol. In VN, before I got my hands on a folding stock M2 Carbine, I had one of these cut down M2 Carbines with a shoulder strap. (photo from the internet) Aside from looking pretty cool, it was about useless for anything except up close and personal. But it does seem like AR pistols are gaining in popularity.



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    VIP Member Array 10thmtn's Avatar
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    Just today some numbnut was shooting a god awful loud AR pistol at the outdoor range a few bays over. It was so loud, my autistic son had to leave the range, despite hearing protection. And the damn thing jammed. Every. Single. Shot.

    I hate those damnable things with the burning heat of a thousand suns.

    And every time I go to the range, idiots have them. They’re loud as hell, and judging by the target results, most people can’t shoot them worth a darn.

    The only thing 5.56 has going for it is velocity. Shooting it through a stumpy barrel is an exercise in noise making...and looking like a wanna be.
    sgb likes this.
    Carry a sidearm always. Be able to put shots into the torso and then head, if needed. The rest is much less important.

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    VIP Member Array Chuck R.'s Avatar
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    I agree with old Chap, IF you're going the pistol route take a hard look at the 300AAC, it out performs the 5.56/.223 in short barrels, and isn't as loud. My 9 1/2" .300AAC sounds about like a 16" 5.56. It's the route I took:



    Makes for a handy light weapon that's effective out to 200 yards or so.

    IF you're going to go with 5.56/.223 stick with at least a 10.5" and if yo're not going to suppress it, at least look at a linear comp. It directs the blast noise FWD, although if you're shooting through/around cover, it still sucks. Whatever you do, don't add a standard compensator.....
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  7. #6
    Distinguished Member Array TSKnight's Avatar
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    Thanks for the replies.

    A friend has a 10.5" AR pistol in 223 that I have shot. It is a little difficult to use one handed. It is front heavy. That is why I was thinking the 7.5" might work better for me, but not if it loses effectiveness.
    With one hand occupied by the cane, I'm looking for working options that won't break my budget.

    I've used the G17 with an Endo brace and had good results out to 50-60 yards. Beyond that, I want a rifle for better effectiveness.
    Democracy:
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  8. #7
    VIP Member Array Chuck808's Avatar
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    No matter what, using one hand to shoot it isnt going to be an effective way of shooting it. Its just too heavy. On top of that, the shorter barrels like 10" and less give up reliability. The dwell time just isnt there. Going from a 10.5" to an 11.5" barrel with a pistol length gas system, youre only adding 1" of barrel length, and gaining about a 40% increase in dwell time. I wouldnt ever go less than 10.5" at an absolute minimum. With a 7.5" youre around 2250fps. The bullet is already below its minimum effective velocity before it even leaves the barrel. Any of that fragmenting and tumbling that you would want out of a defensive round/varminting round, which is generally understood to happen at around 2400fps, likely isnt going to happen. On top of that, with a 55gr bullet, youre only at 618ft/lbs of energy at that velocity.

    If youre looking for a one handed weapon with a bit more punch, maybe go with something like full length 357 Magnum revolver or a 10mm semi-auto. Something like a Glock 40, with a 6" barrel shooting a 150gr Corbon round 1426 fps is going to give you even higher energy, at 677ft/lbs. Furthermore, a 6" barrel revolver will shoot a 125gr Corbon JHP at 1715fps, letting you touch a huge 816ft/lbs of energy. You would need to have a 10" barrel in your AR to finally top it.

    Im a huge fan of 223/556. Its optimal for self defense. But the ONLY thing it has going for it is velocity, and when you start getting under 12", it just doesnt really make much sense.

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    VIP Member Array Havok's Avatar
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    . I have an 8.5" 300blk and its ok, but I prefer a longer barrel. I have an 11.5" 5.56 and I like that. In terms of easy handling, its perfect Much easier for me to hold and better velocity, and reliability than a 7.5. If I shot the 300blk a lot, I would want a 10.5, or something suppressed so I could put a longer handguard on it.
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    VIP Member Array Nmuskier's Avatar
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    I can't see any reason to have a 5.56mm pistol. Even with quality soft points in 70+ gr, you are at a severe performance disadvantage due to the velocity loss. I also do not understand pistol caliber carbines outside of legal compliance. Why give up rifle performance for a pistol cartridge? And that ridiculous pistol conversion apparatus? It looks like the worst of both worlds.

    A 300BLK in 125-145gr out of a 10.5" barrel is highly effective. A threaded muzzle device that projects the gasses forward makes a pistol that is mild to shoot, and keeps it within pistol OAL.

    Palmetto State Armory has pistol uppers and pistol lower parts kits that make assembly easy. There are lots of options. All you need is a lower receiver. The final product is extremely reliable and accurate.
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  12. #11
    Member Array BackpackHunter's Avatar
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    I use a 10.5" 5.56, with a 77gr TMK I get reliable penetration and fragmentation to well beyond 200 yards. Much more than I need out of a pistol.

    Esse quam videri
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  13. #12
    VIP Member Array Havok's Avatar
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    Quote Originally Posted by Nmuskier View Post
    I can't see any reason to have a 5.56mm pistol. Even with quality soft points in 70+ gr, you are at a severe performance disadvantage due to the velocity loss. I also do not understand pistol caliber carbines outside of legal compliance. Why give up rifle performance for a pistol cartridge? And that ridiculous pistol conversion apparatus? It looks like the worst of both worlds.

    A 300BLK in 125-145gr out of a 10.5" barrel is highly effective. A threaded muzzle device that projects the gasses forward makes a pistol that is mild to shoot, and keeps it within pistol OAL.

    Palmetto State Armory has pistol uppers and pistol lower parts kits that make assembly easy. There are lots of options. All you need is a lower receiver. The final product is extremely reliable and accurate.
    Being a "pistol" is nothing more than a legal classification. I can take my SBR upper and put it on a "pistol" lower and it completely changes the legal requirements/infringements while having no difference in capability. As far as the velocity loss, that is dependent on barrel length, not whether its a pistol or rifle. As far as PCC, I think they have less real world relevance these days than they have in the past, but they are still cool. For me the advantage to one would be that I can carry one type of magazine/ammo for both a pistol and rifle. Not sure what the "pistol conversion apparatus" thing is that you're talking about.
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    VIP Member Array Nmuskier's Avatar
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    @Havok a link earlier has one of those gadgets that you put your Glock or M&P pistol into to have a stock. Fun, but doesn't really gain anything in my eyes. If we're adding OAL with a stock, I want barrel length (velocity). I agree that PCC is only cool factor, except where legal restrictions apply.

    The advantage of a pistol AR over SBR is wait time, stamp cost, transport, and states where there are "pistol" permits vs. firearm or weapon permits. For example, I can transport a loaded AR pistol, but not a loaded SBR.

    I don't know that there is a way to have an "SBR upper". There are uppers that make a pistol lower a firearm. Vertical fore grip will make a pistol an NFA item. An SBR can have a side folding stock, etc... Going with an SBR lower certainly avoids these types of restrictions, but I suppose that is what you pay for.
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  15. #14
    VIP Member Array Nmuskier's Avatar
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    Quote Originally Posted by BackpackHunter View Post
    I use a 10.5" 5.56, with a 77gr TMK I get reliable penetration and fragmentation to well beyond 200 yards. Much more than I need out of a pistol.

    Esse quam videri
    77gr 5.56 I am familiar with are designed to mushroom, not fragment. The cannelure in the 55 and 62 gr is what aids reliable fragmentation. The generally accepted velocity for reliable fragmentation is 2700fps mv. Your 77gr in a 10.5" barrel starts out below this. That is the reason for an expanding bullet rather than fragmentation at that bullet weight. Also, the heavier bullet will get better penetration.

    Another problem with shooting 200 yards with a pistol is that most AR rear sights are engineered around 55gr or 62 gr rifle velocities. The sight radius also gives a poor sight picture. A red dot or scope becomes necessary. Open sights need to use the large rear aperture, which is fine for close targets.
    Psalm 144:1

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    Member Array BackpackHunter's Avatar
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    Quote Originally Posted by Nmuskier View Post
    77gr 5.56 I am familiar with are designed to mushroom, not fragment. The cannelure in the 55 and 62 gr is what aids reliable fragmentation. The generally accepted velocity for reliable fragmentation is 2700fps mv. Your 77gr in a 10.5" barrel starts out below this. That is the reason for an expanding bullet rather than fragmentation at that bullet weight. Also, the heavier bullet will get better penetration.

    Another problem with shooting 200 yards with a pistol is that most AR rear sights are engineered around 55gr or 62 gr rifle velocities. The sight radius also gives a poor sight picture. A red dot or scope becomes necessary. Open sights need to use the large rear aperture, which is fine for close targets.
    I am shooting the Black Hills 77gr TMK that is designed to fragment. You are more than welcome to look up the specs on it. In addition to my own testing, there have been numerous tests posted on various forums including AR15.

    Esse quam videri
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