It’s almost become commonplace to hear a story about a 300 Blackout round finding its way into a 5.56 AR pattern rifle (or vise versa).  It seems like this stories have become almost routine to hear among AR enthusiasts, a group that often owns both calibers. Now as most of you already know, this is an easy mistake to make.  Both rounds were designed to use the same magazine, making it easy to slip in the wrong round when you’re not looking.

Note:  Do NOT do this.  This image serves to prove the above point.  

Anyone who thinks this will never happen to them will say something like, “why didn’t you check your ammo before putting it into the gun”.  That’s a cheap cop out, and it doesn’t really solve the problem. Let’s face it, we’ve all shoved that PMAG into our AR’s as quickly as possible, so we can start slinging lead downrange.  We don’t want to stop to make sure that ammo is the right ammo. We’re just trying to have fun at the range. So what’s the easy way?

Use Different Mags

Years back when I decided to adopt 300 Blackout, a gunsmith at a local range recommended that I buy different mags for each caliber, specifically to avoid this mix-up.  Having used this method for years I can tell you it works brilliantly.

Left: Daniel Defense DD Magazine carrying 5.56 ammo

Right: Lancer L5 Advanced Warfighter (in translucent smoke) carrying 300 Blackout ammo

For me, I wasn’t shooting nearly as much 300 Blackout ammo and didn’t need as many dedicated 300 Blackout magazines. I then decided I’d use the Lancer magazines. Already owning a few of these fantastic but expensive magazines, it was the perfect amount dedicated 300 Blackout magazines I needed.  

From there I decided that all my other steel and polymer magazines would be 5.56 only, and it would be as simple as that.  Now when I leave the house, it’s easy for me to find the magazines I need for that day’s shooting activities.

But there’s still one thing to consider.

Ammunition Storage

This might seem silly to talk about, but ammo can get mixed up at any point. I love having my stockpile of ammo, but if I didn’t make an effort to separate these calibers it would be a nightmare.  I’m sure anyone out there can tell the difference between the two calibers based on looks and weight. Still, why take any chance when you can label your ammo storage, and eliminate the possibility of a mix-up almost completely.   

If you prefer a single magazine type, try marking your magazines with tape or some other visual identifier.  Any visual marker that reminds you what caliber that magazine holds.  A paint marking pen (like this one from Sharpie) works very well.

Stay safe out there.