If you've spent any time in online gun forums or hunting circles lately, you've probably seen people asking, "What is the 8.6 Blackout?" Despite the name, this has nothing to do with power grids or electrical outages — it's one of the most talked-about new rifle cartridges to hit the market in years. Here's everything you need to know. The Basics: A New Cartridge Built for Power and Stealth The 8.6 Blackout, sometimes written as 8.6 BLK or 8.6×43mm, is a centerfire rifle cartridge cr …