# Ruger AR556- to 300  Blackout?



## drmajor (Oct 22, 2017)

Will a 300 Blackout work on a Ruger AR556?

Would be nice
To have both calibers.


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## killerv (Oct 23, 2017)

yes, just buy a 300 upper


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## fishtail (Oct 24, 2017)

And get the 16" rifle barrel with the pistol length gas system


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## Jester896 (Oct 24, 2017)

if he does that won't it sling brass so far he can't find it with hypersonic loads?


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## drmajor (Oct 24, 2017)

Why Pistol length gas chamber?


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## transfixer (Oct 24, 2017)

Carbine length would make it much smoother shooting, personally I would want an adjustable gas block,  that way you can tune it to the loads if necessary.


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## drmajor (Oct 24, 2017)

Adjustable gas block?

Suggestions on this?
why?


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## fishtail (Oct 24, 2017)

Certain bullet weights/powder combinations won't cycle with certain length gas systems.
With the pistol length gas system I'm getting good results with supersonic loads using bullet weights from 135gr to 220gr.
As you see, you are going to get a wide range of suggested preferences.


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## Kanook (Oct 24, 2017)

If you only plan on "supers" (super sonic) without a silencer, it really doesn't matter to much.

If you plan on running "supers and subs" with and without a silencer, it seems that a pistol length tube and a adjustable gas block are the best way to go. so you can tune the rifle to the load

I am building an AR pistol and am using an adj gas block because I plan on using both 

There is alot of knowledge over on the 300 forum    http://www.300blktalk.com/forum/


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## Jester896 (Oct 24, 2017)

if I run 125s Supersonic in my pistol length system the brass hits the deflector so hard it bends the case and it lands 15+' away.  If I run 220s subsonic it spits them out almost as far a carbine length system with no dent in case...slightly over gassed is an understatement I think.

drmajor....with the adjustable gas block you would be able to regulate the gas going back in to operate the bolt for either super or subsonic rounds


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## drmajor (Oct 28, 2017)

Same magazines & etc work?

Just need 300 upper?


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## transfixer (Oct 28, 2017)

Yes,  the same mags work for either,  the .300blk is basically a 5.56/.223 case that has been shortened and neck enlarged,  you can actually make your own cases from surplus brass, with the correct dies and something to shorten the cases.


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## Jester896 (Oct 28, 2017)

I have made most of mine from surplus pulls that they damaged the neck on.  I have a chop saw with a vise set up to do it.  Run it in a trim die with a Dillon trimmer attached...then through the size die and check them with a Mo's gauge.

you might want to get mags of a different type than you use for your 5.56 or at least something with a different feel in the dark.  A .330 BLK will chamber in a .223.


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