Nope, I'm not talking about condoms, though I'd say they're a good idea as well, I'm talking about safety glasses and hearing protection.
As a demonstration in regards to wearing safety glasses, I'm reminded of a round of Bulgarian brass cased 7.62x54R which ruptured in my Mosin Nagant M91/30 one day, several months back. When I pulled the trigger there was a weird sound like a high pressure air hose had been cut and my face felt like it did when I got badly sunburned at an air show a few years back. I looked down at my rifle and there was smoke coming out of places where it didn't normally come out of. I worked the bolt and out popped the spent case with a "T" shaped rupture. The bore turned out to be clear so the bullet had made it out just fine. I double checked the rifle just to make sure everything was alright, it was. Those M91/30's are built like tanks. For that matter, most firearms should be able to handle a case rupture. Anyway, a picture of the case is below. I keep it to remind me of the other important firearm safety rules beyond the basic four. If' I hadn't been wearing eye protection I doubt I'd be able to see today.