TommyBuilt HK G36C 300BLK Kit –

Whether you are a HK UMP, XM8 orG36 fan – or a Star Wars superfan (or both) – the builds and conversion services from Tom Bostic and crew will not surprise you. TommyBuilt offers up some of the best HK “clones” of the polymer machine gun and sub machine gun models made outside of Germany. The price to entry can be steep – like the majority of the Keckler & Koch world, but the quality is nothing but top tier.

Tommybuilt has just released a 300Blk plug and play upgrade for the G36C patterned rifles. The kit is for sale through and links as well as details can be found below.

TommyBuilt G36 Conversions Here


TommyBuilt HK G36C 556/223 To .300 Blackout

The Tom Bostic .300 BLK conversion barrel set up is designed to drop in any G36C or Sl8 to G36C conversion and reuse your G36C op-rod/spring set, gas piston & barrel nut. Each set up comes with the custom designed 300 blackout barrel & gas block, replacement recoil rod/spring assembly and a replacement op-rod spring plate (I’ve found that some of factory punched steel H&K plates have burrs that hang up on my gas block, it’s an easy swap if needed.) If this barrel set up is going into a new build you will need a barrel nut, C/K gas piston w/rings and the C op-rod /spring set.

This set up is drop in and you only need the proper barrel wrench for install or you can ship it to TommyBuilt Tactical LLC for the installation. The barrel and gas block are Black Nitride coated for longevity and resistance against wear and corrosion. They are threaded in the standard USA .30 cal 5/8×24 thread pitch and will run both super sonic & subsonic .300 Black ammo. Most subsonic ammo will not properly cycle without a suppressor like most other platforms. All NFA rules apply this is a 9″ barrel and requires an approved form 1 on standard rifles.

MSRP: $874.99



LE – Science – OSINT.
On a mission to make all of my guns as quiet as possible.
Twitter: @gunboxready
Instagram: @tfb_pete


  • Paul

    I’m excited for the 20 civilians in the US who will buy this.

    • Klaus Von Schmitto

      After you have bought a G36 parts kit, an SL8 donor gun, and paid a guy who can actually weld plastic to put them together, the cost of this is a non-issue.

  • JumpIf NotZero

    Oh cool, g36 in 300b – $875 for a barrel wtf! 😀

    I usually go by the rule that it would take me making 10 to be cheaper than just buying 1. But not in this case.

    LOL at HK Clones that aren’t MP5s.

  • LazyReader

    ammunition that’s twice as expensive….nothing says I’m RICH!

    • Anonymoose

      I need one in an XM8! Or maybe 6.8SPC would be more appropriate for an early-2000s mallninja dream gun.

      • JumpIf NotZero

        Ha, remember 6.8? That was funny.

  • Anonymoose
  • elvis

    It won’t cycle subsonic without a suppressor. Where do I sign up?

  • Gus Butts

    I like that .300 Blackout conversion for HK53s better that a company that I can’t recall made, that they designated the C300, if I remember correctly. They are sold for a ridiculous amount but god damn are H&K carbines sexy.

    • Ulysses

      Brethren Arms makes a B300 for $3500, which I can’t help but notice has slowly climbed in price since they introduced it.

      • mig1nc

        Dakota Tactical does too. The D300 runs around the same price.

        • Gus Butts

          That’s what I was thinking about! Not a C300. I love them.

  • Evan

    I’ve shot a G36. It was fun, because full auto is always fun, but it wasn’t overly impressive. I wouldn’t spend whatever absurd amount of money this thing is going for.