.300 BLACKOUT BARREL QUESTION

[codyusaf04]

I already own a 5.56 7.5 inch AR pistol and have been thinking about doing a .300 blackout conversion. My question is, if I were to buy a .300 BLK barrel, gas block, tube,etc….Do I have to do anything special to the upper receiver for it to fit? I would just plan on swapping between 5.56 and .300. Would the .300 barrel be able to plug-n-play (so to speak) with the already complete 5.56 upper? I just wanted to make sure in-case there is something different about the fitment of a larger caliber barrel.

[AFshirt]

The 300 barrel should fit right onto the upper. You might want to consider a new bolt to go along with it to since there is wear between the 5.56 barrel and the lugs on the bolt.

[codyusaf04]

Thanks AFshirt. I appreciated the clarification.

[CaliRider]

Thats my main attraction to 300 blk; everything is the same besides the upper. An AR15 308 is sweet, I dont know why they are not more popular.

[eodinert]

I say build a second upper, but yeah, that's the only difference... a 'pistol' length gas tube, and a new barrel (and a 5/8x24 muzzle attachment).

[Bullz]

Second upper is a nice thought... but then you have the expense of a second hand guard and you almost HAVE to go with a free float since you're dealing with a pistol length gas system. +sights, +muzzle device, etc. You go from a $300ish barrel conversion to a $700 (or more) complete upper.

Unless the existing bolt has a low round count, I would second the idea of picking up a new one with the barrel.

7.5in 5.56 is a good conversion host for a 300blk setup. You'll realize a major performance increase at that barrel length.