I have been getting a lot of emails from Brownells about "new" products (first time I have heard of them, anyway). The set below looks very interesting - foldable piston ARs in .223 Wylde and .300 BLK, in 16" and 10.5" barrels. Seems like they compress the buffer & springs into the upper receiver and therefore the gun can be fired with the stock folded. The barrel is on a hinge so the front end can be folded as well.
I'm guessing these aren't "MA legal" with folding stocks, but this opens up possibilities for an ultra-short pinned stock on an SBR since you don't need space for a buffer tube. A foldable 10.5" barrel in 300BLK would be pretty cool - like a significantly improved, "big boy" version of the Kel-Tek Sub-2000.
LINK
I'm guessing these aren't "MA legal" with folding stocks, but this opens up possibilities for an ultra-short pinned stock on an SBR since you don't need space for a buffer tube. A foldable 10.5" barrel in 300BLK would be pretty cool - like a significantly improved, "big boy" version of the Kel-Tek Sub-2000.
LINK