My 300 AAC Blackout Build

Trinimon

Trinimon

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I wasn't going to get another AR in the safe but having seen the nice price on the Rainier Arms matched upper/lower combo at OST and having all the spare parts from upgrading my DD, I figured, what the heck.

I finally got my upper/lower in yesterday so like a kid with a new box of Lego, I got started on the build.

Total cost of parts purchased: $1085.50 before tax.

Upper/Lower: Rainier Arms from OST
Buffer Tube: Rainier Arms from OST (comes with end plate and castle nut)
Barrel: NEA 12.5" 300AAC Blackout 1:8" twist, polygonal rifling from SFRC (I also have a 10.3" DD 300BLK barrel ordered from Wolverine)
Gas Block: MI low profile (from fellow CGNer) with pistol gas tube (Brownells)
Rail: Daniel Defense 10" Lite Rail from Wolverine
Lower parts: Daniel Defense from Wolverine and from my own DD from earlier upgrades
Muzzle Break/Flash Supressor: PWS Triad from Questar
Grip: Magpul MOE
Stock: Magpul MOE
BCG - Undecided, the one in the pic if from my other AR. Tempted to get a NiB one.
Optics: Looking at getting Troy Battlesights with the HK style front for my BUIS. I'll migrate my Aimpoint Pro to this AR and get a Bushnell 1-4x24mm PCL scope for my DD when they hit the shelves in Canada.


This one sweet matched pair with zero play. Nice flared magwell and tension adjustment screw in the lower receiver.
Upper comes with dustcover and forward assist.
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Got all the parts laid out and ready to assemble.
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Upper 95% completed: Need to torque down the barrel nut and install the rail and muzzle break tonight
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Lower completed: Even paint filled in safety icons.
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I was going to just leave the spare parts in this rifle but but I am missing my Norgon ambi mag release, Geissele trigger, JP Tuned Buffer spring, Spike H2 buffer, Rainier Arms Raptor charging handle and BAD ambi safety lever that are on my DD. Damn it! lol
 
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Sparky369 said:
Nice looking build I have been thinking about doing up a 300 blk build but my question is how do you plan to feed it?
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Feeding them is easy. 223 brass is easily converted to 300BLK and reloading components are no problem. If you don't reload there are a few brands of ammo available but so far the cheapest I've seen is $16/box which means handloads are the best option.

I've posted it in numerous places on the site so I'm not doing it again but if anyone needs some reloading data for 300BLK for shooting in the AR platform PM me, I have lots of testing done with numerous bullet weights and powders. The loads in the books don't all work with a semi auto.
 
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Welcome to the 300blk club.

I use.carbine buffer but I have a spikes heavy buffer arriving today, will let you know how it works out next week.

Suputin I rem sj hardware had some.aac.300 blk 9" uppers a while back and a note with the upper said that aac recommend a h2 buffer
 
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f55 said:
Welcome to the 300blk club.

I use.carbine buffer but I have a spikes heavy buffer arriving today, will let you know how it works out next week.

Suputin I rem sj hardware had some.aac.300 blk 9" uppers a while back and a note with the upper said that aac recommend a h2 buffer
Click to expand...

I run a standard carbine buffer (which came with the rifle) and I've shot everything from 110gr V-max to 208gr BTHP handloads and all cycle perfectly once you use the right powder. My rifle won't cycle the Hornady factory 208gr loads though.
 
Nice Build!

Working on my 300BLK build right now, waiting on NEA 12.5" 300 Barrels to return in stock at SFRC.

I plan to use the Nikon P300 for a scope... just need to find one in Canada, Cabella's or Bass pro should have them.
 
I noticed that the NEA barrels throats are cut to exactly 308 bullet diameter. Guess that might help with accuracy. The barrel lugs and feed ramp are cut pretty sharp and tends to cut into the bullet's jacket but not enough to affect it IMHO. That should smooth out after a few firings.

Nice looking scope. I wish Nikon would use 30mm tubes like everyone else. Getting a Nikon would mean I'd have to buy more scope rings. I got enough 30mm ones already. :p
 
f55 said:
The spikes is for new ar build but I am interested to see what it does for 300blk.
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Let us know how it works out. I don't think it will be any good unless all you shoot is hot supersonic, it's a very gentle recoiling round and if anything a lighter buffer might help out with getting more of the heavier rounds to cycle properly.
 
Barrel: NEA 12.5" 300AAC Blackout 1:8" twist, polygonal rifling from SFRC
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I bought the same, but mine is not polygonal, it's standard rifling.

I used a NEA upper, barrel, gas block and hand guard.

Looks great, shoots great, no hiccups what so ever.
 
Kunundrum said:
Nice Build!

Working on my 300BLK build right now, waiting on NEA 12.5" 300 Barrels to return in stock at SFRC.

I plan to use the Nikon P300 for a scope... just need to find one in Canada, Cabella's or Bass pro should have them.
Click to expand...

That looks like quite a nice scope. Reticle is decent for more precision shooting but what it doesn't have is a close range, illuminated dot type of function.

P-300_Reticle.png



With the HiLux you get both. Zoomed in it has hash marks for more precise aiming and zoomed back to 1x it acts as an illuminated red dot type of sight.

opplanet-leatherwood-hi-lux-illuminated-cmr4-reticle.jpg
 
cr5 said:
Let us know how it works out. I don't think it will be any good unless all you shoot is hot supersonic, it's a very gentle recoiling round and if anything a lighter buffer might help out with getting more of the heavier rounds to cycle properly.
Click to expand...

I will, i did find this w w w.advanced-armament.com/300-BLK-Upper-9-Barrel_p_461.html

No harm in trying :)
 
Cool, do post the results after your range session.

I torqued down my barrel and added the rail and muzzle break. Here's my complete build with a temporary RDS. All ready for the next range session.
Damn this stock trigger blows and as a lefty shooter, I gotta get another Norgon ambi mag release. I keep reaching for it on this rifle only to realize, there ain't one! lol

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Trinimon said:
Cool, do post the results after your range session.

I torqued down my barrel and added the rail and muzzle break. Here's my complete build with a temporary RDS. All ready for the next range session.
Damn this stock trigger blows and as a lefty shooter, I gotta get another Norgon ambi mag release. I keep reaching for it on this rifle only to realize, there ain't one! lol

12200873526_ae71222118_b.jpg
Click to expand...

Nice rifle.

Use your right thumb to trigger the mag release. The mag will drop into your hand just beautifully. As a lefty I have never once felt the need for any upgrades to the AR the way Gene Stoner designed it.
 
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