I agree with others on this. It's easier and cheaper to build your own. You can set it up the way you want, with the parts you want. Just shop it around.
My own SBR
Some slight alterations and with the AAC M4-2000 attached.
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That which does not kill us only makes us stronger. /Nietzche
http://www.OmegaTactical.com
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NRA Certified Pistol, Rifle, Shotgun Instructor