I've not seen any AR's like that, but I have seen some "Colt Commando" (XM177E1) mockups that fit the principle. They had about 12" barrels, with a 5" flash hider welded to the barrel to make it extend to 16 1/2 inches, within legal length. Then after saying that was ok, the ATF "backpedaled" and said ", no, those flash suppressors are REALLY sound suppressors, so NFA weapons, and that 12" barrel REALLY makes the weapon an SBR, so what you've got there is TWO NFA weapons, needing TWO tax stamps".
Duplicitous bastards!
I've no use personally for those sorts of weapons, or what they call now "AR pistols" with barrels between 7" and 10", but no butt stock, just a brace. I think the barrels are too short on those to make full use of the powder in the cartridge, some of it just gets blown out the muzzle before it burns, and is therefore not being used to propel the bullet. So, wasting powder and money, to my way of thinking. However, their money ain't mine to not waste, to each his own, and more power to 'em! I just ain't gonna have one of them is all.
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Duplicitous bastards!
I've no use personally for those sorts of weapons, or what they call now "AR pistols" with barrels between 7" and 10", but no butt stock, just a brace. I think the barrels are too short on those to make full use of the powder in the cartridge, some of it just gets blown out the muzzle before it burns, and is therefore not being used to propel the bullet. So, wasting powder and money, to my way of thinking. However, their money ain't mine to not waste, to each his own, and more power to 'em! I just ain't gonna have one of them is all.
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“Trouble rather the tiger in his lair than the sage among his books. For to you kingdoms and their armies are things mighty and enduring, but to him they are but toys of the moment, to be overturned with the flick of a finger.”
― Gordon R. Dickson, Tactics of Mistake
― Gordon R. Dickson, Tactics of Mistake