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For the best reliability I'm hearing 10.5 inch or longer is best, an 11.5 with a decent buffer tube puts me over 26 inches OAL which ought to allow me to run a vertical forward pistol grip, but then something about a pistol ought to be short (7.5 inch barrel) appeals to me as well...

Decisions, decisions... :)

What says the board, which would you get? BTW this will be a build and not something bought so if anyone has recommendations for buffer tube length and the buffer to run that would be appreciated as well.
 

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I'd get one of those SIG arm stabilizers. :)
 

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mriddick, I just shot the one I built today. its a 7 1/2 inch barrel. I had a problem with short stroking which I attribute to the "pigtail" gas tube. I'm putting in a straight tube and will try again. the buffer is a pistol (carbine) sized setup. if your OAL is 26" I'd just build a carbine and be done with it.
 

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The Kak Industries (http://www.kakindustry.com/ar-15-pa...uffer-tubes/sig-super-sb15-pistol-buffer-tube) buffer tube and a 10.5 inch barrel will put a pistol at 26.5 inches. They also make spacers for the buffer tube that will adjust the Sig brace out a little farther but it does nothing for overall length as far as the ATF is concerned. http://www.kakindustry.com/ar-15-pa...r-tubes-and-parts/pistol-buffer-tubes/sig-lak

If your not set on a vertical grip and will use a Magpul angled fore grip, you can put it on any length pistol. Also, a more vertical receiver pistol grip, like the Magpul K grip, will make the pistol handle better with a SB15 brace. I don't know if you have tried the brace with it strapped to your arm, but it is extremely difficult to use the sights with the pistol held vertical. Holding the pistol sideways though makes it much easier to line up the sights or just put the brace up against your shoulder like everyone else does.

Check out the ballistics on the 300 Black Out in different barrel lengths. It performs well out of a short barrel, better than 5.56.
 

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I am am not sure about this, but I seem to recall that if you add the vertical grip you are going to have problems with the ATF. That is is not considered a pistol, in your case it would be a unlicensed SBR without a stock or other destructive device? You might want to check on that

For the best reliability I'm hearing 10.5 inch or longer is best, an 11.5 with a decent buffer tube puts me over 26 inches OAL which ought to allow me to run a vertical forward pistol grip, but then something about a pistol ought to be short (7.5 inch barrel) appeals to me as well...

Decisions, decisions... :)

What says the board, which would you get? BTW this will be a build and not something bought so if anyone has recommendations for buffer tube length and the buffer to run that would be appreciated as well.
 

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Discussion Starter · #7 ·
I am am not sure about this, but I seem to recall that if you add the vertical grip you are going to have problems with the ATF. That is is not considered a pistol, in your case it would be a unlicensed SBR without a stock or other destructive device? You might want to check on that
A pistol over 26 inches can run a forward pistol grip since by law it can't be a AOW.
 

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What's an AOW?
 

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mriddick, I just shot the one I built today. its a 7 1/2 inch barrel. I had a problem with short stroking which I attribute to the "pigtail" gas tube. I'm putting in a straight tube and will try again. the buffer is a pistol (carbine) sized setup. if your OAL is 26" I'd just build a carbine and be done with it.
I goofed. 26" is an AK with a folding stock in the folded position. an AR with a carbine stock collapsed is 32". my pistol with a 7 1/2 inch barrel is 23" overall. IMO shorter is better. it will be nice to get the bugs worked out of my build so it runs good. muzzle blast is another issue but it cannot be helped with such a short barrel.
 

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the pigtail gas tube encircles the barrel twice on its way to the bolt carrier. a rough measurement comes out to 5+ inches added to the length of the tube. a straight tube is 7 inches. the pigtail is about 13 inches if it were straight. that is longer than the tube on a mid-length upper. I don't think its building enough pressure before the bullet leaves the barrel to work the action properly. I will keep you informed on how this works out.
 

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I purchased a straight 7" gas tube for my pistol to replace the "pigtail". everything works great now. I just got back from the range. 100 rounds in 20 minuets the only stoppage was from a P-mag I tried. god awful muzzle blast though.
nice range toy. so NY50/70 I'd say 7.5" is reliable.
 

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I am going to be trying a 7.5 inch today that I assembled last weekend. Straight gas tube, Carbine length buffer. We will see how she does. Will also be shooting my piston core 15.


Finestkind
 

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Got to shoot both of them today and everything functioned as it should except for one failure to eject 70 rounds which was my fault for running it dry. Got some oil in it and it ran fine. great day all in all.


Finestkind
 
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