All of these attributes line up with what matters when choosing a bear defense rifle — except the cartridge. Most would consider the .223 or 5.56 NATO beneath the threshold of an appropriate bear defense round. I don’t believe these to be the best options for bear defense, but they have longstanding reputations for being effective in this capacity and are generally accepted. Here’s What Actually Makes a Great Bear GunFinal ThoughtsComing away from this, I’m not going to switch to using an AR-15 as my primary bear defense rifle. However, I’m convinced that the AR-15 is a lot more realistic as a bear defense tool than I gave it credit for.