See our ammunition write up on Tactical Gun Review:
SBR (Short Barrel Rifle Load) – This load is specific to short barrel rifle’s with 11″ barrel or LESS. Hornady 208 grain A-max loaded subsonic @ 1050 FPS in 11″ barrel. This load is designed to get top velocity in short barrel rifle’s. Normal 300 Black Out subsonic ammo designed in 16″ barrels will run 900-950 fps (or slower) in short barrel rifle’s. This ammo will get you top velocity, and still remain sub sonic! This load fired in a 16″ barrel will be super sonic! 100 rounds per order.
Brass is once-fired Lake City (LC), 5.56 brass cleaned, sized and cut down to 300 Black Out spec. Hodgdon or Alliant powder and primed with CCI #400 small rifle primer. Standard 1:8″ twist or faster (1:7″ twist) will stabilize this bullet.
100 rounds per order.
The 208 A-max is officially discontinued from Hornady.