AR15 in 300whisper/blackout?

Laeger

December 19, 2012 09:41

On a s&w mp15 ar in 300whisper , could that be converted to a 223 with just a barrel or would you need to change the whole upper?

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  62fuelie

  December 19, 2012 10:09

  The 300 Whisper and the 300 Blackout are both based on the 221 Remington Fireball case, which is a shortened .222/.223/5.56X45 case so the case head is the same and the same bolt can be used. You could swap out the barrel and probably have a running 5.56, but it strikes me as a whole lot of extra work. I would buy an upper without the bolt carrier group and charging handle and change them as I wished just by pushing the take-down pins out, but that's just me.

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  tsr1965

  December 19, 2012 12:12

  Laeger,
  
  Yes, you would need the barrel, and the corresponding gas block, barrel extension, and gas tube. Then the barrel, with the barrel extension installed, and bolt would have to be headspaced.
  
  However, that 300 Blackout, is a pretty neat round, and if I were in your shoes making that decision, I would just get another upper.
  
  Best

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  cpermd

  December 19, 2012 14:15

  Just a barrel change will work
  But what a PITA
  Just get another upper

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  sandwarrior

  December 20, 2012 11:18

  As others have noted, a barrel change will work, but along with the barrel you also need the tools and know how to make it happen.
  
  That said, I would just get another upper in .223. While you're at it consider the upper end power you can get from the platform and consider one of those if money will allow.

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  beantownshootah

  December 21, 2012 06:28

  quote:Originally posted by Laeger
  On a s&w mp15 ar in 300whisper , could that be converted to a 223 with just a barrel or would you need to change the whole upper?
  
  
  Its a little more complicated than unscrewing the old barrel and screwing in a new one, but with a few caveats, yes you can do this conversion without having to get a whole new upper.
  
  The biggest real world problem here is that it takes specialized tools and some knowledge to change barrels, and if you don't have these things, its probably not cost effective to get them for one swap.
  
  Then, once you do the conversion, its just not going to be practical to reverse it every time you want to change calibers. So this is what I suggest.
  
  If you have no interest in a 300 Whisper gun, probably the simplest/easiest thing to do is just to sell the .300 upper and use the money you get to buy one in .223. Do that and you may have money in your pocket left over when its done.
  
  In fact, you may even be able to find someone willing to just swap you a .223 upper in exchange for a .300 whisper upper (maybe even plus cash or mags, or some other goodie you want). Since the upper isn't legally a gun, this can be done with no paperwork and you can even have an upper mailed directly to your home if you like.
  
  If you DO want a 300 Whisper gun (and it is a pretty cool caliber), then again, switching barrels and other parts back and forth between .223 and .300 every time you want to change calibers simply won't be practical. If that's the case, just buy a second .223 upper.
  
  In terms of total cost, buying an upper is going to be a little more expensive than converting the gun, but you'll have a lot more flexibility to shoot what you want, when you want, and I think you'll be happier in the long run.

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