Build a 300 Blackout AR Upper

[BR8818]

I would 1:7 pistol length gas. If you want an AGB Riflespeed, SLR, or Superlative Arms are the best I've found. Like DDadams said if you only plan on shooting supers you probably don't need an AGB.

I haven't used this exact BA barrel, but the price is pretty good.

Ballistic Advantage 16″ .300 Blackout Pistol Length AR 15 Barrel, (Modern Series)

This .300 Blackout chambered 16 inch Modern Series Barrel is machined from 4150 Chrome Moly Vanadium steel with a QPQ Corrosion Resistant Finish and QPQ coated M4 feed ramp extension. Additional Info Length 16

bkingsfirearms.com

 

[DadSmith]

Thank you all for your help.

One last consideration.
Gas system length.
Carbine or Pistol?
I tried to research this and it seems both work for supers, but is one better than the other for supers? Which one would you all recommend? This will be a 16" barrel for 125gr-150gr Supers. Main purpose is deer hunting, possibly self defense if it came to that.

 

[BR8818]

Thank you all for your help.

One last consideration.
Gas system length.
Carbine or Pistol?
I tried to research this and it seems both work for supers, but is one better than the other for supers? Which one would you all recommend? This will be a 16" barrel for 125gr-150gr Supers. Main purpose is deer hunting, possibly self defense if it came to that.

I would definitely go pistol gas length. I'd rather have "too much" gas with a pistol length system, and have to tune it with an AGB/ heavier buffer. Then having to open up the gas port on a carbine length system to try and get a specific load to cycle. Plus it'll give you the opportunity to cycle subsonics if you ever want to.

 

[Cavman]

Thank you all for your help.

One last consideration.
Gas system length.
Carbine or Pistol?
I tried to research this and it seems both work for supers, but is one better than the other for supers? Which one would you all recommend? This will be a 16" barrel for 125gr-150gr Supers. Main purpose is deer hunting, possibly self defense if it came to that.

The pistol length is whats best. Way if ya ever wanna run subs ya can no problem especially without adjustable gas block. The rounds you're looking at for deer will work. But in the .300blk world it seems the barnes vtac 110grain reign Supreme. I used 150grain my 1st season. Definitely didntt get the results I do with the 110s. Plus being all copper they really petal out and keep the weight on inpact. Plus ya can use cheaper 110 vmax bullets to.help sight in or self defense or plink with.

 

[Jarvitron]

Pistol length is definitely the way to go. I had a carbine length barrel and struggled to get subs to cycle right (there may have been other issues with the setup), but I have had two pistol length uppers and they both worked great with subs and supers.

 

[DefenseInsight]

Look at what well know rifle/upper makers do and do that.

I'd check out Sionics and BCM.

 

[papa6x]

I built my 300BO some time ago. I went with a Wilson Combat 16" Recon contour 1/8" barrel with a carbine length gas tube and a non adjustable low profile gas block. I haven't had any problems with it cycling subs . I'm planning on getting a suppressor this year, so I've worked on some loads for that and it runs fine with those. A real good source of info can be found here, one the developers of the 300 used to be on there. It's been a while since I've been on there.

 

[G19G26]

I've got everything I need except for barrel, adjustable gas block, and tube. I'm just trying to figure out what I need to get barrel twist rate wise, and gas system length to run the lighter bullets.
Thank you for the offer though.

Do you happen to know the twist rate on that barrel?

Check with Ballistic Advantage, tell them what you want to use it for. They'll set you up. BTW, my 10.5" blkout shoots like dream with 220gr and it is subsonic