Bison Armory is producing a custom 6.8mm 200 grain bullet designed specifically to for 6.8mm SPC subsonic loads. The very long bullet requires a fast 1:7″ rifling twist. From Bison Armory …

The 16” BSP barrel with its 1:7” twist is only offered in our Recon profile with a carbine length gas system, for reliable subsonic action cycling. Both subsonic and full power 6.8 SPC ammunition can be used with 6.8 BSP rifles, which makes them extraordinarily versatile weapons.

The closest competitor to the 6.8 BSP is the .300 Blackout. The Blackout shoots 220 to 240 grain bullets when operating subsonic, compared with our 200 grain 6.8 BSP bullet. Because muzzle energy is linearly proportional to bullet mass, the Blackout does have a slight advantage in muzzle energy when operating subsonic.

But the .300 Blackout’s edge disappears quickly when things speed up. When operating with full power 6.8 SPC cartridges, the 6.8 BSP clearly dominates the Blackout by every measure, including muzzle energy, down-range energy, trajectory, and effective range.