300 Blackout

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rodney1968

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I just ordered a Rock River Arms 300 blackout upper, never had a blackout.
Just wanted to be sure will it fit on .556 lower? and do I need different mags?
I noticed pmag makes one for blackout but I thought the .556 ones would work.
any other info appreciated
 
It will fit and you can use regular mags.

Be sure you mark your mags in a way that you know they are loaded with 300blk. I only use 10 or 20rd mags in mine. I save the 30rd mags for 5.56.
 
Yeah pins right on a mil-spec lower and feeds out of regular mags. Killed 5 deer with mine last season and all 5 DRT. Love mine.
 
kcult said:
It will fit and you can use regular mags.

Be sure you mark your mags in a way that you know they are loaded with 300blk. I only use 10 or 20rd mags in mine. I save the 30rd mags for 5.56.
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Like Kcult said! Don't accidentally mix up the ammo... A 5.56 round in the .300blk upper could ruin your new upper and your face at the same time...
 
Yup, it'll fit just fine. Be extremely OCD on keeping the ammo segregated. Bad things happen when mix occurs.

Then again, if you wanted an AK power level round, why not just go 7.62x39? Sorry guys, I can't bring myself to get on the Blackout bandwagon.
 
rodney1968 said:
I just ordered a Rock River Arms 300 blackout upper, never had a blackout.
Just wanted to be sure will it fit on .556 lower? and do I need different mags?
I noticed pmag makes one for blackout but I thought the .556 ones would work.
any other info appreciated
Click to expand...

There have been reports of some magpul 5.56's not chambering as well, so they developed the 300 BO mag to fix the problem.

But as has been alluded to above.....dropping a 30 caliber bullet into a 223 barrel is really bad Ju-Ju!
 
Alabamacoastie said:
Like Kcult said! Don't accidentally mix up the ammo... A 5.56 round in the .300blk upper could ruin your new upper and your face at the same time...
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Eh, it wouldn’t be the best idea to shoot a 5.56 in a .300 upper but I doubt it would hurt anything. Now doing the reverse would absolutely ruin your gun and possibly face.
 
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Dave951 said:
Yup, it'll fit just fine. Be extremely OCD on keeping the ammo segregated. Bad things happen when mix occurs.

Then again, if you wanted an AK power level round, why not just go 7.62x39? Sorry guys, I can't bring myself to get on the Blackout bandwagon.
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Because lowers are different.


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B00ger said:
Because lowers are different.


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the mags are different but x39 definitely works in a standard ar-15 lower
 
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Dave951 said:
Yup, it'll fit just fine. Be extremely OCD on keeping the ammo segregated. Bad things happen when mix occurs.

Then again, if you wanted an AK power level round, why not just go 7.62x39? Sorry guys, I can't bring myself to get on the Blackout bandwagon.
Click to expand...
7.62x39 does not suppress as well as 300bo. If you are not suppressing then there is no reason to go 300bo imho.
 
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BigWaylon said:
Huh?

7.62x39 upper works on a standard AR-15 lower.

Or did I misunderstand your comment?
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I misunderstood the nature of the comment I was meaning to make so it came out as a comment that doubly looked wrong but confusing and filled with stupid. It happens.
 
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