Smith & Wesson M&P15 300 Whisper (.300 AAC BLK)

Smith & Wesson have launched their first .300 AAC BLK rifle and complete upper receiver assembly. The M&P15 300 Whisper is listed as compatible with the .300 Whisper and .300 AAC Blackout cartridges (The .300 AAC BLK is the new SAAMI, trademark-free, version of the .300 Whisper)

Model M&P15 .300 Whisper

The complete rifle is designed with hunting in mind. It is finished in Realtree APG and comes with a 10-round magazine. The 1:7.5″ twist is compatible with 110 to 220+ grain bullets. Its MSRP is $1,119.

The upper features a 10″ free-float quad rail and a Yankee Hill Phantom flash hider. It has a MSRP of $819.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • strongarm

    Beretta’s are the fore-runner of Gas Operated Shotguns in Europe
    and all with the feature of “Shell Release Button” from the first
    beginning to the last specimen. Their production started nearly same
    time period wiith the USA, at beginning of 1960’s and loading actions
    should be made with a mechanical measure permitting to load the Shell Chamber automaticaly when intentionally required. This was made in
    accordance with a Government Regulation of that times and Shell Release
    Button was for this purpose and still being made for an additional
    safety for the time being. Usual Button was a pin at in front of top of
    Trigger Guard.

    Gas Operated Beretta’s were thought for hunting purposes and their
    Gas Mechanism designed with a piston located in front of the tube
    magazine as liimiting the shell capasity. This, also limits their effective
    use in security purposes and happens the sole drawback of these first
    quality gas operated shotguns in service use.

    • strongarm

      This comment wrıtten for Beretta XPlor. Please locate the correct
      place or wipe ıt off.

  • Josh

    Now only if we had something to shoot out of it. That would be Awesome!

    • crosswiredmind

      300BLK ammo is available online and the UMC branded rounds come out this month.

  • Andy from West Haven

    Um, I was told it was safe to shoot .300 Whisper out of a .300 BLK but not vice versa. The case varies slightly in favor of the BLK for this.

    Was I misinformed?

  • Robert

    “Um, I was told it was safe to shoot .300 Whisper out of a .300 BLK but not vice versa. The case varies slightly in favor of the BLK for this.

    Was I misinformed?”

    No, you are correct, but the S&W rifles are actually 300 AAC BLACKOUT rifles internally that S&W is branding as 300 Whisper(R). Yes, it is confusing.

    • Andy from West Haven

      Thanks Robert. *facepalm* S&W. Still, it’s nice to see. With this I hope ammunition manufacturers get in line and start producing. EITHER cartridge.

  • MarkM

    It’s either a .300 BK or it isn’t. With SAMMI involved, it can’t be both.

    What’s “marked on the barrel?” That’s all that counts, because that spells out who’s getting royalties or not.

    Last I heard, JDG owned .300 Whisper, and Remington set up .300 BLK as SAMMI. That means the gun industry can use it for free as long as they stick to the dimensions of the official drawing.

    As a 6.8SPCII / 6.8×43 owner, the difference SAMMI designation makes is significant. Ask JDG what they think of it.

    • Robert

      They are marking both on the barrel. I think they are treating it like marking 5.56mm/223 on their barrels. Agreed, it would be better to not confuse people and just mark them 300 AAC BLACKOUT or 300 BLK. Even 5.56mm/223 has been confusing for decades.

      • It is annoying they are not just labeling it .300 BLK.

        Robert, do you know if the folks behind the .300 Whisper are now letting manufacturers use the trademark for free or at a low cost?

      • Robert

        I have not heard anything about changes in Whisper(R) licensing.

    • If JDJ has a trademark on “Whisper”, then all that he can prevent is the use of the marking regardless of dimensions. A trademark does not allow one to prevent someone from making a functionally identical item.

  • Other Steve

    Robert, since I know your the guy to ask 😉

    Why did S&W choose 1:7.5? When everyone else seems good to go at 1:8? Is it something that works because they are 16″ barrels? Is tree any benefit to a 9″ 1:7.5? Maybe for 220+ handloads?

    • Robert

      I don’t know why they picked that. Maybe they asked SSK and that is what he recommended? I don’t see any negative to doing 1/7.5 twist. I shot 1/7 for accuracy with supersonic and it was exactly the same results as with 1/8.

      • Other Steve

        Perhaps you get a couple inches more penetration before tumble on soft stuff with 1:7 on 220gr?

        1:7.5 seems like a compromise then. I’ll still be down for an AAC 9″ when they start coming with the new KAC URX III rail. Those look great!

    • Robert

      The 9″ AAC is currently shipping with the 8″ URX-III – though check with the dealer to make sure which one you get.

  • Lance

    Looks nice to use with a suppressor.

  • Matt G.

    LOL. Those prices are hilarious! Please please no-one buy these. I could very easily build an entire rifle out of great parts for what they are asking for the upper with the big ass yhm rail.

    The camo one looks stupid. “well camo the plasticy parts and the receivers because it’s easy but the rest ain’t happening” also doesn’t the BLK use a piston length gas system for all barrel lengths?

    • Robert

      Carbine length gas is best for a 16 inch barrel. Pistol length gas is needed for any barrel under 16 inches.

    • fw226

      Well, I got my M&P for a lot less than the MSRP. I assume it will be similar for this.

    • JamesD

      But… but… but… it’s a Smith & Wesson!
      It couldn’t possibly be as good if it doesn’t have the S&W logo on it!

  • Dan

    I’ve really liked the 300 blackouts I’ve shot. They sound so good with a can on.

    • Matt G.

      Seriously. I shot a Remington rep’s full-auto BLK rifle at a match awhile back. He let me run it through one of the room clearing stages. It was dead sexy, extremely fun.

  • Joe nobody

    That sucks I just finished the paperwork on my .300 whisper ar upper suppressed, and now I find out that .300 blk cant be used in it which makes me think that .300 will go extinct soon.

    • Robert

      No big deal – you can run a 300 BLK reamer in it and then shoot any BLK ammo. If you can’t do that yourself, there are a few places who will do it for $50. It is the same process as making a 223 rifle rated for 5.56mm.

  • jd

    For that kind of money you’d think it would come with a rail system better than UTG.

    • Matt G.

      Is it really a utg? I can’t tell by the picture but the logo looks longer than utg’s and it doesnt look much like the utg rail I bought a long time ago.

      I would be pretty disappointed if that’s what it is.

  • Ken

    What do you hunt with this round?

    • Matt G.

      I would feel comfortable taking deer within a hundred yards with this round.(not with the subsonics) remember it has the velocity and energy of the 30-30. Hogs are another good use for this round.

      Most of all of course, this round is excellent for culling the zombie horde when using the subsonics at night.

  • jd

    Yes it’s UTG. It’s their newest rail system. It’s manufactured in the US by an unknown company. It’s not following MIL1913 standards and it’s still making profits for a foreign airsoft company but it looks like they’re heading in a much better direction.