300 Blackout gas block? Part recommendations.

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Xfire68

New member
I was going to just buy a complete upper but I got a great deal on a 300 BO DD CHF 16" barrel and now need pretty much everything else to finish a upper.

Is there anything I should be looking for in a gas block for 300 bo? Is a standard AR 15 block just fine? Never built a upper let alone a 300 BO upper.

I have a YHM Diamond rail, barrel and gas tube but, I need everything else. Recommendations are welcome.
 
R

rightside

New member
I built an AR in 7.62 x39. I figured the 223 carbine length gas hole would be to large and I believe it was because the recoil seemed excessive. I installed an adjustable block and it tamed it down very nicely and still functions correctly. Does take a little trial and error to get the gas correct so it cycles properly while not beating your weapon to pieces at the same time. If I had gone with the mid-length gas system it might have been better, but I wanted the features on this particular barrel. Don't know how this may translate to the 300 BLK OUT. Good luck.
 
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Xfire68

New member
Thanks for the insight. I thought I may run into issues with the port size. I will have to look a little deeper into what is working on others 300 BO's. I had no idea that low profile gas blocks could be so expensive!

Again if anyone else would like to chime in please do.
 
M

mavracer

New member
I used a standard lo-profile gas block on my 16" carbine length gas Alpha Sports barrel it does just fine with supersonics havent tried any subs.
 
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Xfire68

New member
Thanks Mavracer. I was hoping that would be the case as I hate buying parts I will never use (I have a ton)! I am trying to part together a mid grade to high quality upper. I think the barrel was a good start and don't want to skimp on the minor parts if "The higher priced stuff" makes a difference in overall fit and function?
 
S

Sharkbite

New member
Checkout 300blktalk.com. Everything you wanna know about the cartridge and rifles that shoot it

Im there under the same user name

The same gas block as used in a stock 223 gun works perfectly. No need for the expense of an adj gas block. With a carbine length gas system you will be on the edge of being UNDERGASSED with alot of loads. Using an adj gas block turned down will only make this worse

Unlike 223 and even 7.62x39 guns the blackout is never overgassed. Totally different powders used (even pistol powders like Reddot and Unique).

Its a different animal then a 223 gun and the usual "fixes" sometimes mess things up
 
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Xfire68

New member
No Mavracer only Supers. The option to shoot suppressed is out because I live in IL and Subs don't really appeal to me for whatever reason?
 
X

Xfire68

New member
Ordered a BCM upper receiver, Manticore Nightbreak comp, YHM LP Gas Block, YHM Diamond Specter length rail and some LWRC rail skins. That and the Daniel Defense CHF 16" barrel should make for a nice 300 Blackout upper! Total cost was $480 shipped for everything.

Thanks for the help guys.
 
M

mavracer

New member
If you're only gonna shoot supersonic that setup should be great.
Hopefully you reload as it makes the blackout a lotta fun cause it'll shoot any 30 cal bullet that you can find on sale pretty damn good.
Right now I'm using 168gr match blems from midway @ ~1750 fps they shoot a little over an inch at 100 with a 3X optic.
 
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TMD

New member
I have three .300bo uppers. two of them are 16" and one is an 11". If your upper has a carbine length gas port which it most likely has any standard gas block will work with super and sub loads. The great thing about the .300bo is the only thing needed to switch over a 5.56/.223 is the barrel. Everything else is interchangeable.
 
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Xfire68

New member
Yes Mavracer, I reload. I have a number of presses and load 8 calibers.

I also process 5.56mm, convert .300 Blackout brass to sell. All once fired government auction once fired Lake City.

Thanks again guys for the tips and info.
 
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Xfire68

New member
Hey Mav, I have a pretty good amount of .300 Blackout load data but, was just wondering which powder you prefer?
 
M

mavracer

New member
H110/WW296, I really haven't experimented much though only other powder I tried was 5744, performance was a little better with the ball powder and I don't have to weigh each one.
I really want to try some subs with unique.
 
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Xfire68

New member
I have had no luck finding a 8lb jug of H110. I have 2lbs of it but that is what I use for 44Mag.

I was thinking of trying 4227?
 
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Sharkbite

New member
I use 4227 for all my supersonic loads in 300blk. Mostly 125gn-150gn bullets.

I find it to be easier to ignite uniformly then H110/296, esp in COLD weather. More uniform velocities
 
X

Xfire68

New member
Thanks Sharkbite! I like what you're saying there!

I keep searching for H110 for 300 BO but also as my main 44 Mag powder but, it looks like 4227 works extremely well in 44Mag as well.
 
X

Xfire68

New member
Forgot to add I received my rail, gas block and upper receiver today.

That was some fast shipping! I ordered it Monday night!

I am really loving the look of the rail as I am so used to Magpul furniture.

I am still waiting for the barrel and comp.
 
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