The 300blk is quite interesting to me.

It seems to offer roughly .30-30 performance in a much smaller and potentially less expensive form factor (considering .300blk is basically a .223 cartridge with a .308 bullet).

That means it could end up being an excellent hunting cartridge for the same type of game one would use .30-30 on (like Deer).

As another added benefit, it will work in any firearm .223 will, as long as you can switch out the barrels and ensure proper headspace. No need for special magazines and bolts.

All in all, it sounds like it has the potential to become a very popular cartridge if they're able to market it to the hunting community and not just the 'tacticool' market.