5.56/300 blackout set

Cbrem · May 20, 2017

Wondering about thoughts on this. Hopefully I can post the link (I'm technologically deficient).
Seems like a great idea to me.
https://m.facebook.com/HyperionArms...47903667290/741099039405506/?type=3&source=48

Pinecone · May 21, 2017

Until you pop a mag for .300 BO into the lower with the .223 upper installed.

It WILL chamber and fire the .300 round. ONE ROUND.

outrider58 · May 21, 2017

Pinecone said:
Until you pop a mag for .300 BO into the lower with the .223 upper installed.

It WILL chamber and fire the .300 round. ONE ROUND.

I see how that could get a little confusing. I prefer the idea of having a dedicated lower for your 300 Blk. :thumbsup:

GolfR · May 21, 2017

Pinecone said:
Until you pop a mag for .300 BO into the lower with the .223 upper installed.

It WILL chamber and fire the .300 round. ONE ROUND.

That's exactly why I have put these on all my guns.

https://www.customardustcover.com/Calibers_c_27.html

It doesn't prevent you from loading the wrong ammo but it is a visual reminder of what upper is on the gun. I put red tape around the mags that I use for 300 blk and make sure that I use dedicated mags for different ammo. It costs a little more but a heck of a lot less than buying a new gun and the potential hospital bills.

teratos · May 21, 2017

outrider58 said:
I see how that could get a little confusing. I prefer the idea of having a dedicated lower for your 300 Blk.

I have 2 rifles set up identically. 1 is .300BLK, the other is 5.56mm. I got the little engraved dust covers and engraved mag catches with the calibers on them.

HordesOfKailas · May 21, 2017

I use rail covers to identify different uppers.

lazarus · May 21, 2017

outrider58 said:
I see how that could get a little confusing. I prefer the idea of having a dedicated lower for your 300 Blk.

I haven't gone none .223 wylde for my ARs yet, but I don't plan to mix and match lowers. A 6.5 Grendel build is in my plans for next year, but it'll live on its own lower even though the ammo won't interchange at all, I'd prefer to still keep chances down of inserting the wrong mag.

Different calibers I'll only interchange like calibers on the same lower(s) and they also get their own easy to identify magazines (either completely different style or different color).

Cbrem · May 21, 2017

the custom dust covers sound like a great idea,

Major03 · May 21, 2017

Stencils work too

outrider58 · May 22, 2017

Cbrem said:
the custom dust covers sound like a great idea,

I would need more than just that, but that's just me.

John from MD · May 22, 2017

This subject got me concerned so I did some mixing of components.

I ran a non scientific test to see if this was a dangerous combination as I have different caliber uppers. I made up cartridges for .223 and 300 BO with a primer but no powder. I tried mix and match in my uppers and could not get either to chamber in the other calibers chamber. They were almost 1/4 inch out of battery so I don't see any chance of ignition.

I use 150 gn bullets in the 300 which may make a difference. I don't have any shorter bullets to try so I don't know if the store bought 120's would be a problem. None of the primers detonated during my testing.

outrider58 · May 22, 2017

John from MD said:
This subject got me concerned so I did some mixing of components.

I ran a non scientific test to see if this was a dangerous combination as I have different caliber uppers. I made up cartridges for .223 and 300 BO with a primer but no powder. I tried mix and match in my uppers and could not get either to chamber in the other calibers chamber. They were almost 1/4 inch out of battery so I don't see any chance of ignition.

I use 150 gn bullets in the 300 which may make a difference. I don't have any shorter bullets to try so I don't know if the store bought 120's would be a problem. None of the primers detonated during my testing.

Interesting...

Magnumite · May 22, 2017

John from MD said:
This subject got me concerned so I did some mixing of components.

I ran a non scientific test to see if this was a dangerous combination as I have different caliber uppers. I made up cartridges for .223 and 300 BO with a primer but no powder. I tried mix and match in my uppers and could not get either to chamber in the other calibers chamber. They were almost 1/4 inch out of battery so I don't see any chance of ignition.

I use 150 gn bullets in the 300 which may make a difference. I don't have any shorter bullets to try so I don't know if the store bought 120's would be a problem. None of the primers detonated during my testing.

This is what I like. Thanks. Actually trying to chamber opposite calibers. I was thinking hard about the 300 BO...
I work late today but if I think about when I get home tonight I'll try to chamber a 7mm TCU. It shouldn't chamber in the 5.56 since the shoulder is blown forward.

Magnumite · May 22, 2017

Now that I think about it, a 7mm TCU barrel would be interesting, though essentially duplicating the 300 AAC.

EDIT: Its been done. #00 is more versatile.

omegared24 · May 22, 2017

I have a marked dust cover on my 300BLK upper. All 5.56/.223 aren't marked.

John from MD · May 22, 2017

Magnumite said:
Now that I think about it, a 7mm TCU barrel would be interesting, though essentially duplicating the 300 AAC.

EDIT: Its been done. #00 is more versatile.

I loved the 7mmTCU when I was into TC Contenders and silhouettes. It is an awesome caliber.

DaemonAssassin · May 22, 2017

Bloody hell.... For 1500, you could build a 300BLK AR and a 556 AR.

jimbobborg · May 22, 2017

John from MD said:
This subject got me concerned so I did some mixing of components.

I ran a non scientific test to see if this was a dangerous combination as I have different caliber uppers. I made up cartridges for .223 and 300 BO with a primer but no powder. I tried mix and match in my uppers and could not get either to chamber in the other calibers chamber. They were almost 1/4 inch out of battery so I don't see any chance of ignition.

I use 150 gn bullets in the 300 which may make a difference. I don't have any shorter bullets to try so I don't know if the store bought 120's would be a problem. None of the primers detonated during my testing.

So how did you load the 300 into the 5.56 chamber? Did you release the bolt via bolt catch or release with the charging handle? Some of the .308 bullets are skinny enough to chamber into a 5.56. See the first picture on this search https://www.google.com/search?q=300...20&bih=1085#tbm=isch&q=300+blk+chambered+.223

John from MD · May 22, 2017

I released both calibers from a locked bolt and a mag fed round. I did say that some lighter bullets may have a problem but I don't shoot any so I didn't have any to test. I use 150 gn jacketed and lead bullets and they won't chamber.

Pinecone · May 22, 2017

outrider58 said:
I see how that could get a little confusing. I prefer the idea of having a dedicated lower for your 300 Blk.

I made my .300 BO AR a different color.

5.56/300 blackout set

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