I've wanted a 300 Blackout upper or rifle for a while. I know the ammo is expensive, but this appears to be a very good deal. I've had a PSA carbine and put together a nice mid-length last year. I like their build quality and never had a problem with reliability. So, if you're looking for a 300 Blackout this might meet your needs.
http://palmettostatearmory.com/index.php/psa-16-chf-300aac-blackout-freedom-rifle.html
16" Barrel Length
300 AAC Blackout Chamber
1 in 8" twist
"Machine-gun" Steel Barrel
CHF Barrel
HPT/MPI Barrel
SQR 13.5" Lightweight Rail
Forged Upper & Lower
Polished Combat trigger
Magazine
Lock
http://palmettostatearmory.com/index.php/psa-16-chf-300aac-blackout-freedom-rifle.html
16" Barrel Length
300 AAC Blackout Chamber
1 in 8" twist
"Machine-gun" Steel Barrel
CHF Barrel
HPT/MPI Barrel
SQR 13.5" Lightweight Rail
Forged Upper & Lower
Polished Combat trigger
Magazine
Lock