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300 Blackout build

Phasma2956

Private
Minuteman
Nov 28, 2012
2
0
48
Hello, does anyone have any advice on building a 300 blackout AR? I have a friend that gave me a deal on a spike tactical lower that I couldn’t pass up. My problem is that I don’t know how to build one properly. I have looked online and have not come up with anything helpful about the combination of parts to use or the rifle twist that I would need. I will be shooting 115 to 125 gr rounds around 100 to 250 yards and thinking about getting a suppressor in the future. Thank you in advance for any advice you have to give.
 
Re: 300 Blackout build

You just buy a barrel and all of the other parts are the same as 5.56mm.

The barrel you get may require a special short gas tube, but it depends on the brand barrel you get.
 
Re: 300 Blackout build

Mr. Silvers is correct. Most of the twist rates are 1:8 but there are some makers that are switching over to a 1:7 in order to better stabilize heavier subsonic bullets (i.e. greater than 220gr). If you're only interested in supersonics in the weight you mentioned, either twist will be fine.

If you plan on getting a 16" barrel, you could get either a carbine or pistol length gas system. This will depend on the barrel maker. Just buy the correct length gas tube length. Otherwise, the rest of the parts and assembly is the same as a 5.56 upper.
 
Re: 300 Blackout build

Silvers ought to be correct! The blackout is a lot of fun and very effective on wild pigs. The cool thing is only the barrel is different. 223 bolt, magazines work without modification. I made mine with a LAR side charging upper and a JP adjustable gas block. I can shut off the gas that way and basically have a bolt action, very quiet with a suppressor that way! By all means get a can (if you still can) that's where this thing really shines. My barrel is a CMMG 16" with a carbine length gas system one in eight twist which has worked good for me with anything from 110 to 220 grain ammo
 
Re: 300 Blackout build

Thank you all for the input and advice! I want to do it right the first time and appreciate all the help I can get.
 
Re: 300 Blackout build

I'd be patient in your search for parts. If not it's going to cost a lot more to build.