The crew at Mad Dog Weapon Systems have put together a promising new wildcat cartridge, the .277 Wolverine. The cartridge uses 5.56 NATO and .223 Remington brass along with 6.8mm Remington SPC bullets to produce a cartridge that’s philosophically the same as 300 AAC Blackout but serves a different purpose.
It’s the same in that the only difference between a 5.56 rifle and a .277 Wolverine is the barrel. The bolt, receiver and magazines are all 5.56/.223. But with a larger .27-caliber bullet, a gun chambered for .277 Wolverine is better-suited for hunting and possibly for self-defense, as the larger impact surface is potentially more likely to expand than fragment, depending on the bullet design. Unlike 300 BLK it’s not a dual-purpose round with a sub-sonic side.
They have a full line of components to build a gun chambered for .277 Wolverine, including ARs and bolt-action rifles, along with loading dies to make cartridges. While production ammo isn’t available just yet, there is enough interest in .277 Wolverine to make it a reality in the future.
To help early adopters there is also a working .277 Wolverine forum.