What happens when you shoot 300 BLK in your 5.56 AR ?

[GunnyUSMC]

My .277 Wolverine is the only rifle I have in OD green. For mags I only use OD green Hex Mags.

 

[H&R Glock]

The first picture of the cut away barrel had me in awe of the person who has a milling machine and cutter bits that can so accurately bare the elongated bullet in the barrel. I also marvel at the cut away 5.56 chamber in Sota's pictures. Mister Machinist, you're the man! Ya' learn something new every day! Thanks

 

[ColoradoMinuteMan]

Gunny,

I’m using a similar concept. Have .277 WLV in OD, mark the upper, mark the magazine, color code the magazine. As you mentioned, one of the several benefits of the .277 WLV is that they will not chamber in a 5.56 chamber.

The first picture of the cut away barrel had me in awe of the person who has a milling machine and cutter bits that can so accurately bare the elongated bullet in the barrel. I also marvel at the cut away 5.56 chamber in Sota's pictures. Mister Machinist, you're the man! Ya' learn something new every day! Thanks

 

[Sistema1927]

I keep them separate by:

1) Never taking both 5.56 & 300 AAC to the range at the same time.
2) Only using mags with 300 AAC labels for 300 AAC ammo.
3) Using some common sense and never letting my guard down.

 

[FL-NC]

I don't have a 300 B-O AR but a friend has one. To avoid such a mistake, be built his 300 rifle using the desert tan magpul furniture on the stock, pistol grip, and railed handguard, and the same tan mags stenciled 300 B-O (his 5.56 AR and mags are black). Also, he loads all of his mags at home the day before he goes to the range, and keeps them separated in his range bag in different compartments. Minor inconveniences to prevent major potentially expensive and dangerous problems. I color code my different Glock mags for 9 and 40.

 

[cfullgraf]

That's why I used engraved ejection port covers on oddball calibers.

View attachment 788560

I've used commercially available items such as these dust covers where available to indicate different cartridge chamberings in some of my ARs.

Where commercially available items are not available, I've also made stencils with my vinyl cutting machine and painted the chambering on the upper with Duracoat.

Finally, I put a laminated stock on my 308 Win Garand to differentiate it from the others. Not that a 30-06 round could chamber in a 308 Win chamber, I do not want to chamber a 308 Win round in the 30-06 chamber.

 

[GunnyUSMC]

Tactical Gear Junkie is a great place to get engraved dust covers. They even offer custom engraving.
https://tacticalgearjunkie.com/pages/search-results-page?collection=ar15-ejection-port-covers

 

[kozak6]

A few years back, I was loading a magazine for my CZ52 pistol. All of a sudden, the hairs on the back of my neck stood up and it felt like the world tilted. Something was wrong. Very wrong. I set the magazine down, stepped back, took a deep breath, and looked around.

The box of 9mm was next to the box of 7.62x25 on the tailgate.

I unloaded that magazine and there it was. A round of 9mm had snuck in. And it would have chambered. And fired.

At the last gun show, I saw a blown up Makarov. It was pretty cheap, but with a quick google of probable replacement parts, not cheap enough. Of course, there's also the fact that it was a blown up Makarov. How do you even do that?!? The sell blamed Chinese ammo, but that seems unlikely.

 

[lysanderxiii]

300 Blackout - PMags
5.56mm - aluminum

Now, I can tell 'em apart in the dark. you

 

[Walkalong]

I used a 300 Blackout marked upper I found online somewhere, and load my rounds longer than some folks, but mostly rely on my being safe and using the right ammo in the right gun

 

[rbernie]

300 Blackout - PMags
5.56mm - aluminum

Now, I can tell 'em apart in the dark

Not only do I use dust cover markings, I also use this specific magazine approach.