Finally Finished: My Suppressed 300 AAC Blackout SBR

HuntingRifle2

And just in time for hunting season, too! I’ve just put the finishing touches on my new favorite rifle of all time and I wanted to share my excitement with you all. Ever since I visited the Advanced Armament guys in 2011, I knew that I needed to get my hands on a suppressed 300 BLK SBR. They showed me the light, and turned me into a massive 300 BLK fanboy – you may have noticed. A rifle that’s more compact than an MP5SD, but just as quiet and more powerful? Sign me up! John Hollister himself even took me to the range to make that comparison . . .

First, full auto is tons of fun. Second, pink shirts are sexy. And third, that comparison sold me on the concept of the caliber.

Some calibers do better in longer barrels. The 5.56 NATO round, for example, is designed to burn all of its powder in 20″ of barrel. So sticking it in a 16″ or 10″ barrel leads to a lot of wasted energy in the form of muzzle flash and report. With the 300 BLK round, though, it’s the opposite problem. The round is designed to completely burn its powder in 9″ of barrel, which means my old 16″ 300 BLK barrel was unnecessarily long.

My only mistake in building this rifle was waiting so damned long to start the SBR paperwork. I procrastinated, figuring that the 16″ barrel with the silencer was good enough and I could get by without another tax stamp. But as time went on, I found myself still lusting for a shorter package. Maybe that didn’t come out the way I intended it. Anyway, a year after I submitted the form for my silencer, I submitted one for my SBR as well. And nearly two years after my trip to AAC, the rifle is finally complete.

As soon as I got the new upper, my first stop was the range. And it performed exactly as I remembered.

Percieved recoil is no more than with the 16″ version. It’s also just as quiet, meaning that I still don’t need hearing protection to go hunting and don’t have to worry about annoying the neighbors. And as for accuracy?

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With subsonic rounds, I was making the steel gong sing at 250 yards. With supersonic rounds, 500 yards was a breeze.

For optics, I went with the Leupold Mark AR Mod 1 with the SPR reticle. I reviewed this scope a while back, and you can still see the same scope that I reviewed sitting on my competition AR-15 in the background. I liked it so much that I bought the scope from Leupold after the review. And then I bought another for the 300 BLK rifle, too. Hint: it’s a really nice scope, especially for the money.

As for internals, that’s a Franklin Armory lower receiver with an ALG defense QMS trigger. The lower was chosen because I liked the design, and the guys at FA were able to engrave my trust info into the gun before anodizing it. As for the trigger, the ALG defense QMS is a good single stage trigger that I had lying around. The upper receiver is the 9″ complete upper from AAC. And the silencer is the 762-SDN-6 from AAC.

I guess I should wrap up this article by passing on some advice that I learned the hard way. If I learned anything, it’s not to procrastinate on submitting your forms to the ATF. The longer you wait, the longer you wait. If your heart is calling for an SBR, just do it! Then one day, your dreams will come true.

comments

  1. avatar Stu says:

    I’ve wanted to get a .300blk barrel for my LMT for a year, but it will be years before that shop starts cranking out mrp barrels again

    1. avatar BnGRacing says:

      There’s a few companies out there that can machine a standard AR barrel so it can work in a LMT MRP. Do a search at the usual places and you should get the info you need. Hell, call LMT or shoot them an email. Because of the Great Panic of 2012, they may help you out more than you’d expect when it comes to what/where/how to get a barrel machined to work with their rifles.

      Good luck.

  2. avatar Matt in FL says:

    I LOVE that the sound of the trigger reset is almost as loud as the gun’s report, or that the report is almost as quiet as the reset. What kind of trigger do you have in it?

    That is a sexy rifle, and I’m almost insane with jealousy. I’ve been trying to decide what to build my two Spikes Florida lowers out as, and now I know what one is gonna be.

    1. avatar Matt in FL says:

      Actually, can you give a quick rundown of whose components you used, and if there was a specific reason why, what that reason was? I’m specifically interested in the suppressor, forend/rails, and internals.

      1. avatar Nick Leghorn says:

        Edited the article to add the details.

        1. avatar Matt in FL says:

          Thanks!

  3. avatar Gtfoxy says:

    I want to suppress my 6.8!

    Suppressors are legal for hunting here in WI.

    1. avatar Southernmutt says:

      If you really want a hushed 6.8, Bison Armory has 1:7″ uppers/ barrels for subsonic use.

      What kind of ammo are you planning on running? I’ve heard good stuff about Hornady’s 120SST’s and Federal’s new MSR 115gr while running cans.

  4. avatar daveR says:

    That’s very nice!

    If I had the money, that would be the rifle I would build.

  5. avatar Swarf says:

    You know, there are some pretty accurate dB meter apps for smart phones (I use SPL meter), if you can find the time Nick, it would be very interesting to get some comparative readings from your new toy and some other unsuppressed rifles.

  6. avatar Mediocrates says:

    I asked Piers Morgan, and he said NOBODY hunts with those!

    1. avatar WA_2A says:

      Yeah, and Dianne Feinstein says there’s no earthly reason to own one! She knows what’s better for me more than I do, right guys?

  7. avatar CarlosT says:

    Oh man, I wish Washington didn’t have the stupid law against SBRs and SBSs. I’d probably do a PS90 SBR first, just because of the fan factor, but something like this would be next.

    1. avatar WA_2A says:

      :'(

    2. avatar g says:

      This. I’m generally satisfied with life in WA except for the whole SBR restriction… sucks. Time to start lobbying!

    3. avatar Snuffy 18 says:

      Check your WA gun laws. Suppressors are legal as are sbrs and sbsgs.

      1. avatar Cam in Tacoma says:

        Actually, as of the time I write this, SBRs are still no go in Washington State unless you’re producing(with proper licenses) for military and law enforcement.

        There was an attempt made at getting it changed this year but it died. The effort is going to be restarted next session. The effort is being made by the same guys that got the suppressor law changed.

  8. avatar Saul Feldstein says:

    How much does ammo cost for that sweet machine?

    1. avatar Nick Leghorn says:

      Little under a dollar a round, normally for factory ammo. But reloading keeps it around $0.40/round for match grade ammo.

  9. avatar Tom in Oregon says:

    Huge fan here of the 300. I learned how to make my brass from one of Mr. Leghorns YouTube videos.
    Nick, if you are still loading your own, how about a follow up post on powder, charge, bullet weight, chrono work. I know it’s asking a lot, but you’ll get more trigger time…

    1. avatar John Bergmann says:

      Yes please!!

    2. avatar Vorpalis says:

      I vote for this, too. I’d like to hear first-hand experience of reloading this, what equipment / components you use, which you’ve learned to hate and why. More! More! More!

  10. avatar steven says:

    Nick,

    Dumb question but will the 300 suppressor work with 556?

    1. avatar Tom in Oregon says:

      Hmmm. Great question. Not dumb at all.

    2. avatar Nick Leghorn says:

      Yes. Yes it will. This silencer works on every single rifle I own.

    3. avatar Matt in FL says:

      It’s not as effective as a dedicated 5.56 silencer, but it will still make a healthy difference.

  11. avatar Blehtastic says:

    I want it!

    All the good lawyers I’ve talked to charge around $750 to set up a trust. Not in my price range right now.

    I’d put a longer rail on that thing if you can, something that covers where the suppressor meets the barrel. Would you be able to easily take the suppressor off if you did that? I dunno, but it’d look sexier.

    1. avatar Nick Leghorn says:

      It would look sexier, but I prefer being able to move the can between guns.

      They charged me about $200 to set up a trust down here in San Antonio.

  12. avatar Dan Baum says:

    The only thing missing from this report is the total price tag. Also interested as well in the price and availability of the cartridges.

    1. avatar Nick Leghorn says:

      Upper: $1,100
      Lower: $212.50
      Lower parts: $200
      Scope: $400
      Flashlight and mount: $200
      Silencer: $1,080
      Tax stamps: $400

      Back of the napkin math here. $3,600 for the whole thing, I believe.

      1. avatar CarlosT says:

        Hunting with unobstructed hearing: priceless.

  13. avatar WA_2A says:

    But as time went on, I found myself still lusting for a shorter package.

    You should trade with James Yeager.

  14. avatar Ralph says:

    I’d love to have a suppressed rifle. Unfortunately, such possession would be a crime in the Comintern of Massachusetts.

    It’s kinda crazy. With the NFA stamp and no LEO objection, I could own a machine gun but not a suppressor. Not in this looney-tune state. Well, what can one expect from a place that elects Kennedys with monotonous regularity no matter how drunk or drug-addled they are?

  15. avatar JW says:

    Nick… Spell check error… “Percieved”… I before e except after c.

    1. avatar Dan Baum says:

      Or when sounded as “a” as in neighbor or weigh.Not that that applies here….

  16. avatar ScottyV says:

    Great looking piece there Nick, and we all thank you for no ruining it with a gratuitous ad for one of your sponsors!!!!!

  17. avatar Sean says:

    Hmm nice rifle, I don’t have the time, patience or money to deal with the ATF though 🙁 Is getting it in an SBR an essential for performance, because I was thinking of getting a .300 rifle in a 16 inch or pistol version and then doing the ATF paperwork as time and money permit for the suppressor.

  18. avatar Mark says:

    Nice rifle Nick! I am a big fan of 300 blackout – I just built a rifle for my cousin but he lost his job so I have to sell it. Don’t mean to try hijack your post but I could use the money…
    http://www.gunbroker.com/Auction/ViewItem.aspx?Item=345862598

  19. avatar Charles says:

    “But as time went on, I found myself still lusting for a shorter package. Maybe that didn’t come out the way I intended it.”

    I love that you acknowledged this but kept it in anyway.

  20. avatar Vorpalis says:

    Nice pony, Nick! I think I’m finally sold on .300BLK, and now I’ll have to have one of my own. That “Ffft!” sound just makes me giggle. Oh yes, she will be mine.

  21. avatar missing_the_cheese says:

    Nick,
    With the KAC rail used with this upper can you add rail space to the 6 O’Clock if you wanted to run an AFG or Vertical Grip?

  22. avatar Paelorian says:

    “The round is designed to completely burn its powder in 9″ of barrel, which means my old 16″ 300 BLK barrel was unnecessarily long.”

    Incorrect. According to data available right here on TTAG (see Jim Barret’s “SBR Caliber Showdown: 5.56/.223 vs. 300 BLK” 7/26/2013), 115gr 300BLK out of a 16″ barrel has 24% more energy than the same ammo from a 9″ barrel. 9″ might get the job, done, but that’s a very significant difference. Especially for hunting larger game like deer where the 300BLK’s power is just barely adequate and 24% more energy would be a good idea. I wouldn’t lose that extra energy unless I had good reason to want an SBR, such as a rifle built for handling in tight spaces or for stowing or concealing in small containers.

    1. avatar Mad A says:

      What about with heavier grain subsonic rounds? That’s what one is more likely to shoot suppressed

  23. avatar Josh H says:

    Isn’t this the same video you used to demonstrate the JP captured buffer? I bought one and I love it.

    But the real reason I’m commenting is because “around $0.40/round for match grade ammo.” ?????!!!!!

    Holy hell! I’m getting right at 50 cents a round using Carolina brass and m80 pulls from gunbroker. I realize that price drops with multiple loadings, but I’m curious if you were talking about first loads. What projectiles are you using that are considered match grade that are also cheaper?

    I could probably do 30ish cents a round with picked up brass, but I’ll happily pay the extra 20 cents a round for first loads just to not have to cut and process anything.

    I’m not in any way calling you a liar, I’m just seeing if you can save me a little more money while not having to listen to the loud ass harbor freight saw for a few hours sometimes, while still cranking out match grade rounds.

  24. avatar Kyle R says:

    Nick, why kind of scope mount did you use? Might have the greatest scope on earth (and that you may have), but if it is not on a good, solid base, it’s just a fancy paperweight. Thanks.

  25. avatar Ken says:

    I’m curious about the full auto. Was that an AAC rifle with demo auto sear or was it yours and if so what process did you take to convert/register it? I assume it’s AAC’s.

    Nice ride though, that’s my first purchase soon as my trust is complete.

  26. avatar Nick Staudenmyer says:

    Hey Nick, How long is your rail? I’m getting SBR stamp starting with the lower, and trying to get a good rail length so I can still access the SDN-6 release to take it off.

  27. avatar jereme turner says:

    What sub round were you using? factory, or hand load?

  28. avatar Dave Armstrong says:

    I’m considering this scope for a 300 Blackout SBR build – waiting for the Form 1 approval. It has been nearly 2 years since this post. Would you mind telling me if you’re still happy with the Leupold or have you found something you prefer as a replacement? I’m leaning that direction but can always use more input.

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