300 Blackout Help

[Robert King]

I'm seriously considering building a 300 BO for shooting suppressed. Would probably be 90% sub-sonic but will retain the ability to shoot supersonic as well. I will not be reloading and would most likely shoot Freedom Munitions ammo. I have a host upper I would cannibalize for the build.

All I need to swap out on a .223 upper is the barrel, correct? I can continue to use my JP LMOS BCG with JP Bolt, correct? I would probably go with a SLR or SYRAC adjustable gas block.

I don't want to wait on another stamp, so I'm thinking a Faxon or Odinworks 16" barrel with carbine gas. Any other suggestions on barrel choices or other build considerations?

[Tom Freeman]

You can continue to use the LMOS carrier but a standard weight carrier or even an M-16 carrier will help when the rifle gets dirty. Shooting suppressed it will get dirty. Keep adding oil. Lots of it.

The 300 Whisper is best when you reload.

[mic2377]

If you want to mainly shoot suppressed... do yourself a favor and get a barrel with a pistol gas system. A carbine gas may or may not cycle well with subsonics, but no matter what the pistol gas will give you a lot more latitude to function reliably with subs. I experimented with both, and ended up with a Noveske 16" pistol gas barrel. With a properly sized gas port, no adjustable gas is necessary. I have shot every combination through my Noveske with good reliability.

The lightweight carrier is not necessarily your friend. There are 3 levels of dirty - unsuppressed, suppressed, and subsonic suppressed. Subsonic suppressed makes for the filthiest rifle imaginably and I could easily foresee problems with functioning with a lightweight system.

I would take up reloading because you will see HUGE cost savings with subsonic ammo. My upper will run subs with anything from 190 gr HPBT's to 230 gr cast bullets, and my 0.35 to 0.40 cent/round subs are a WAYYY better deal than $25+/box factory subsonic ammo.

[RogueNathan]

I'm seriously considering building a 300 BO for shooting suppressed. Would probably be 90% sub-sonic but will retain the ability to shoot supersonic as well. I will not be reloading and would most likely shoot Freedom Munitions ammo. I have a host upper I would cannibalize for the build.

All I need to swap out on a .223 upper is the barrel, correct? I can continue to use my JP LMOS BCG with JP Bolt, correct? I would probably go with a SLR or SYRAC adjustable gas block.

I don't want to wait on another stamp, so I'm thinking a Faxon or Odinworks 16" barrel with carbine gas. Any other suggestions on barrel choices or other build considerations?

Nope. Think you are good!

[jtaylor996]

I just built one, but without the suppressor for now. Just build it with an 8" ish barrel using the sig brace. There's really no reason to register an SBR anymore, since pistols have no paperwork to cross state lines, etc.

16" bbl plus a can makes a pretty unwieldy gun, IMO. (I built mine for home defense).

Also, IMO, 300blk doesn't work unless you reload if you're not Scrooge McDuck.

A good place to chat is 300blktalk.com. The designers of the 300blk round and lots of industry guys are on there a lot. It's been a really helpful place to me.

[jtaylor996]

I just wanted to add that my build was done as cheaply as possible, like all PSA parts except a few. I'm even using a $79 PSA barrel. And then when I got it to the range, it's just about the most accurate AR I've ever shot. I'm not kidding a little bit. This is simply an amazing round at anything less than 100yd distance.

I'm not kidding, seriously. Better groups with that 8.5" $79 PSA barrel using el cheapo Fiocchi ammo than my 223 race gun with the Nordic barrel.

I plan on putting a can on it (likely the Omega), and at some point I may need to put in a JP silent captured spring (really makes the gun quiet when shooting suppressed).

I don't know anybody who hasn't gone to 300BLK and isn't just blown away by the results. You won't regret it.

But my advice is to use stock cheap parts instead of your race parts. I can give you a link where you can get the PSA BCG/CH combo for $99 any day, and you don't want adjustable gas on this gun. All 300BLK should be pistol gas systems. The whole thing has been designed around this, and they did a good job here so tweaking mass of components doesn't end up benefitting much, just introducing reliability issues.

[Robert King]

I ended up getting a 10.5" Odin with pistol gas. Will be building it this weekend and putting it on a pistol lower for now. I'll start another form 1 from my trust to sbr a lower I have laying around. A couple months and I'll be able to use it as it should be used.

[JoshF]

Been shooting an 8" 300 BO for two years now. I'm using a Noveske barrel with their gas block as they seem to nail gas port size. The rifle is ran 90% suppressed with an H2 buffer both super and subs and cycles everything with the can off or on. If you are going 300 BO do yourself a favor and get a 8-10" barrel. You gain very little from anything longer and with a suppressor it keeps the rifle's size manageable. Keep in mind 300BO can be expensive to shoot so it's not really a "plinker". Mine is used as a deer rifle for tree stand/blind use where it's awesome. Also I've got around 1300rnds through mine so far without cleaning and I've done nothing but add oil to it. Gun has been 100% reliable. So pick your barrel/gasblock/buffer combo carefully.

Edited May 20, 2015 by JoshF