Home CMMG 300 Blackout Barrel Lengths and Affects on Velocity. Silencer School EP.5

300 Blackout Barrel Lengths and Affects on Velocity. Silencer School EP.5

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In this video we take a look at the affect of barrel length on velocity with subsonic 300 Blackout.

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45 COMMENTS

  4. I am going to tell you something. I worked hundreds of shootings in Dallas as a detective. I know that sounds crazy, but it is true. I wish I had kept my books we logged our activity in. But I did not and did not tally the 12 years.

    I started in 1986. That is about the time 9mm came out. All the hoodrats shot hardball rounds. I learned from experience if someone was hit, even in the torso with a 9, they had a real good chance of making it. That is because bullet did not expand. And the doctors at Parkland hospital could pop someone open and patch them up, even their hearts at times they lived. They were absolutely amazing.

    As an aside, Parkland was grossly overcrowded and a real mess back in the day. People shot, stabbed, wrecked out, beat, you name it on gurneys on both sides of the halls on Friday and Saturday nights. The young interns and nurses were very, very busy.

    I thought the interns were the worst from their doctor programs. But I learned Parkland was the place that only took the best and brightest. That is because every intern wanted to get to PMH because, as one young intern told me, they could get as much experience in a year at PMH as they would do the rest of their career in a nice suburb somewhere.

    But I digress.

    I also learned if someone was hit in the torso with a .45 to go ahead and notify my friends in our office who worked homicides only. With hardball rounds the would channel was large enough they did not have a very good chance.

    I know that all sounds crazy but we had crime like you read about in the mid 80s and early 90s. 500 killed in 1991. Exactly. We had 498 on new years eve and were wondering if would hit 500. Two volunteered and before the clock hit midnight we had 500. You can probably still look it up.

    But people living shot in the torso with 9mm came to a sudden halt when expanding, not hardball rounds came on the scene. They MIGHT make it with one shot, but if they were hit with 2 or more good, expanding rounds I called my friends.

    I know everyone knows to some degree but it is the size of the wound channel that is the deciding factor. Of course with high velocity rounds there is also hydrostatic shock. But that is another subject.

    Get good expanding rounds and use a 300 BO with confidence for self defense, hogs, deer, anything you can put metal on in the torso. Trust me.

  7. What are the biological significant speeds/energies needed for the bullet to operate successfully which is really the goal? So, if the bullet expands as created at all these speeds/energies…then the differences are NOT biologically relevant until you add in the another variable likely, distance.

  15. I don't want to poo poo your entire channel but measuring velocities and then putting a silencer is both useless and stupid. If you want to measure a 7 inch barrel you measure it as is. A silencer will in most cases give the expanding gasses more time to act on the projectile.

  16. I didn’t know the difference between red box and blue box CB 300blk subs other than reman vs new. Curious if the blue box has a bit more oomph since the red box is generally underpowered and can make LRBHO on a few of my 300blk hosts…dicey with a low backpressure can.

  17. I have a Christiansen Arms 300blk MPP, 7.5" barrel. Running it with a Deadair Sandman S, works fantastic so far. Hearing safe but not quite as quiet as I'd like. Looking into semi auto 300blks…. Might go with the MCX, don't know yet. Dang they're expensive….

  21. You guys should do the same test with the same 4 barrels but using a supersonic defensive load like a Hornady 110 VMax. Many of us like to shoot both subs and supers and those should theoretically show a greater velocity difference between barrel lengths. It would be neat to see!

  23. I would really like to hear an explination about why 1-5 twist is better for 300 blakcout. I don't think I'd be able to find anything tighter than 1-7. faster twist rates are used to stabalize heavier bullets, and your're never shooting anything heavier than 150 grain. more comonly 120 grain. evern so 300 blk is the only 3 caliber rifle cartrage being shot at lower velocites out of a shorter barrel. I am curious and would like to hear why you've made this claim.

  25. I had a 300 BLK with 10.5 barrel. Going to build another upper and want to push right to the edge of subsonic with barrel length.
    16" too long to consistently stay under subsonic?
    What about a 12"

  27. I'm glad this video already existed, I was thinking about getting / building a blackout but it has to be consistently subsonic so I'm planning on going for 8" or less so there is no chance of random supersonics to blow my ears out. The way I see it, if I wanted to run supers only, I could use the much cheaper 5.56 I already have.

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