LMT – Confined Space Weapon

Chambered in 300 BLK, the CSW300 from Lewis Machine & Tool combines their Monolithic Rail Platform upper receiver with the Modular Ambidextrous Rifle System – Light Automatic (MARS-LA) lower receiver. It measures 24″ overall with a barrel length of about 8″.

The integral suppressor is based on the Lewis Livermore National Lab Virtual Baffle System geometry. When fired, the gas creates a region of high pressure within a cylinder in the suppressor and then forces the gas into an outer chamber before being expelled out the front of the suppressor.

11 Responses to “LMT – Confined Space Weapon”

  1. Pro Patria says:

    “Lewis Livermore National Lab Virtual Baffle System geometry.”

    Would love to here more about that!

    • Kyle Kata says:

      1950s tech iirc. Was originally designed for taking the blast on aircraft guns.

      Look at the Gemtech MK9K, only “modern” commercial can that uses that system that I know of.

      It’s a coxial system. The blast baffle is a cone and directs gas to one large outer chamber. All the other baffles are in a tube inside that. It’s alright if you have a lot of volume to work with. Which in this case means their actual silencer baffles were at most something like a 1.125” tube or so, probably closer to 1”.

      Considering 300blk is so easy to suppress, I’m guessing they did this to keep the back pressure low.

      But not sticking at least a little of the can out the handguard sure does look dumb.

  2. TheScrutineer says:

    The title said “LMT – Confined Space Weapon” and I read,


  3. Alpha2 says:

    You couldn’t have stuck the suppressor out a half inch? Looks odd.

  4. SVGC says:

    For everyone saying that they should’ve stuck the suppressor out of the hand guard, look at the SURG requirements, especially on the parts regarding contact burns.

    SURG has to prevent operator contact or sustained contact burns from the suppressor (or equivalent) through 1 layer of standard military duty uniform material after firing 210 rounds in 7 minutes at a rate of 1 round every 2 seconds ± 0.2 seconds. A contact burn will be defined as a peak temperature over 160°F in 1 second of contact. A sustained contact burn will be defined as a peak temperature over 160°F in 5 seconds of contact.

    Not saying this solution solved those very stringent requirements but the suppressor exposed definitely would not have.

  5. Matt says:

    That thing is seriously channeling the E-11 “Stormtrooper” Blaster.

  6. lmt fan says:

    LMT makes excellent weapon systems. Have had a MRP CQB for years that has never failed me and has many thousands of rounds through it. Would never hesitate to purchase another if it struck me. Their quick change barrel system also makes cleaning a breeze..or changing calibers.

  7. AbnMedOps says:

    I think it’s Lawrence ( not Lewis) Livermore Nation Laboratories, out near Dublin, CA. They stockpile giant brains there.