Home CMMG 300 Blackout Plan & Build Project!! This should Be FUN!!!!

300 Blackout Plan & Build Project!! This should Be FUN!!!!

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When you set out to build a rifle or pistol, have a plan or objective of what you want to achieve. Don’t ever throw away a spare part because those parts will eventually make their way to another build project.

Primary Arms Gen II 3X Compact Prism Scope ACSS CQB 7.62×39/300 Blackout
Streamlight 88066 Pro Tac Rail Mount HL-X
PSA MOE SBA3 Lower Build Kit, Black
Ballistic Advantage Modern Series 10.5″ 300 BLK
Guntec USA 10″ Air-Lok Series Compression Handguard

Streamlight

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28 COMMENTS

  1. Question: I'm in the process of building a 300 bo. I already have a 9" barrel. Does the rail need to be shorter than the rail? I'm torn if a 9" rail would be just as okay as a 8.5". Nice channel just found you. Cheers

  2. I'm a late in the game as far as comments and subscription is concerned. That said, I'm in the middle of 300 build where I'm using a 9" Ballistic Advantage barrel and I have a SureFire Warcomp on the way.

  3. Howdy KB 32,
    I mentioned earlier that I am building almost the identical 300BLK!! Do you have any idea if I can check headspace with my 223/556 gauges ?? I’m using the exact same barrel as you, with a Palmetto premium nitrate coated BCG…
    Sorry to keep pestering you, but, we all need to be safe, right??
    Thanks Again,
    WarDawg

  4. Hey KB32, Great build, same as I am collecting for, even the receiver and barrel!!
    One question, which did you choose for the buffer & spring?? H1 ? H2 ?? I have heard several different things about them, need your expert opinion if you don’t mind!! Thanks Kota, keep up the great job you’re doing 👍👍🔟

  5. Looks pretty nice.
    Have you ever done an AR build in 7.62×39?
    I'm considering it as I like the AR platform a lot. However I don't care for 5.56 or .223cal. I have other firearms in 7.62×39 and don't want to increase the number of different calibers of ammunition that I have to stock.

  6. Can't wait to see this build done!
    Also, great job with the BA barrel! I've used several and they are extremely accurate. More accurate than I am, haha.
    That Lantac is going to be extremely LOUD though! Had one on a 10.5" 5.56 build back in 2016 and it was ridiculously loud! However, did it's job with the mitigation beyond expectations!
    Great job! Airborne!

  7. Primary Arms has the best products, customer service, and lightning quick shipping in the business! I bought their Bear Creek Arsenal 10.5" m-lock 300 blackout complete upper for one of my pistols. Awesome price, and I ordered it on a Friday and it was on my porch on the following Monday!! I need to investigate their optics….

  8. That's exactly what I'm doing. I building my first AR pistol. I bought a PSA fluted pistol buffer with end plate. But it doesn't use a castle nut. I think I bought the wrong buffer tube. I want to put a SBR 3 on it. Can you recommend a buffer tube that would fit the SBR brace ?

  9. Ive got that same exact hand guard on my 10.5 begara barreled 300 blackout pistol. Its funny because I had the 2.5x primary arms prism Anderson receivers almost the exact build lol. I recently pulled the 2.5x acss off and replaced it with  their new 1x acss prism scope. Jury is still out on the 1x initial thoughts is its a lot lighter than the 2.5x and works great it was actually zeroed from the factory never even took the turret caps off dead on at 50 yards. Only downside ive found is the reticle is kinda small and a little hard to use the ranging ladder.

  10. Just curious, why a pistol length gas system as opposed to a carbine length gas system.
    10.5 in. gives you that option. And are you using a H1 or H2 buffer. If it's a heavy profile Barrel, I have heard you need to use an H2 buffer.

  11. I used so many of the same parts and mounts for my 10.5 300blk pistol. SB brace wasn't out then though so I have the blade. I love it and I was just looking at putting that optic on it cause I just got the 556 version and it's pretty awesome.

  12. 300 blackout is amazing at most realistic fighting distances. I use ammoseek to find it cheap in bulk. Cant wait to see your review. I found my 10.5 BA barrel to be really accurate with the american eagle and remmington you can get at Walmart also. 🤘

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