Kawaii & Fierce

There is nothing like this currently on the market: a complete 5″ 556 upper receiver ready to drop in and use!

This completed upper comes equipped with a Holosun HS503CU optic, Surefire Warden, Surefire Socom Brake (for extra loudness), our rail mounted tactical flashlight and a few other bells and whistles that no other company currently offers.

A Tactical Work of Art

It’s fun to look at this but it’s more fun to shoot!

It’s loud! Like -everyone at the range will stop and look over at you when you shoot this, LOUD!

It’s fun! Like -after the people at the range realized that no, a grenade didn’t just go off, they’ll want to shoot it too!

What’s Included?

There are a few different options to choose from, but all of these options contains the same Mini 5″ 556 Complete Upper.

Complete Upper Components

  • KTactical BAT Charging Handle
  • F-1 Firearms TiN Coated 556 BCG
  • KTactical AR15 Upper Receiver 7075
  • KTactical Anti-Rotation Insert (Red)
  • SLR Rifleworks ION 4.25″ MLOK Handguard 7075
  • KTactical 5″ TiN Coated Barrel (1/6 Twist 5R Rifling)
  • Surefire SOCOM Muzzle Brake

Additional Accessories / Kit Options

  • Holosun HS503CU
  • 3 Slot MLOK Rail 7075
  • SLR Rifleworks Handstop Mod1
  • Surefire Warden
  • KTactical Rail Light
  • Pistol Brace Kit
  • Fortis K2 (Red) Locking Castle Nut Kit

Only the Highest Quality

We did not cheap out on ANY component of this upper receiver. All the parts are of the highest quality.

This was designed so that most people would not want to replace any part of this upper with something else (of course you can do whatever you want).

All of this comes pre-assembled, test fired, and the gas block is tuned to work perfectly with our H3 Buffer and Low Power Flat Spring!

Flawless Performance

What is keyholing? Keyholing is when the bullet looses its stability in flight and begins to tumble in the air. Obviously this is not good for long range or accuracy. Sometimes the bullet will hit a target and leave an ovular shaped hole in the target, sometimes called a keyhole.

Unlike other micro 556 uppers, we did not experience any keyholing with our upper up to 25 yards out. Our Micro 5″ 556 AR upper is accurate and precise (for a 5″ barrel)!

Yes Lockback! Unlike other micro upper receivers that claim “no lockback” as if it’s some kind of feature, our Kawaii 5″ Micro Upper locks back on the last shot!

Just use our H3 Buffer and Low Power Flat Spring!

Note: If you are using something like a BAD lever or extended / ambidextrous bolt catch you might not have bolt lockback on the final shot.

Note: The flat buffer spring is a modified, low power, flat wire spring. We STRONGLY recommend only using our low power spring + H3 buffer combo for optimal performance. 

  • The upper receiver comes fully assembled (according to the kit that your ordered).

    However, the lower parts and other accessories will need to be assembled by the end user (assuming your kit includes any lower parts such as: trigger, buffer, spring, etc.)

  • These kits do NOT contain any parts that require shipment to an FFL.

    There are some shipping restrictions to certain states and cities which can be checked at checkout when entering your zip code, and depending on which kit you selected.

  • Yes. All of our uppers are test fired and function tested before they are shipped out.

    For test firing and function checking, we test using Federal .223 55gr FMJ.

    If you notice any carbon or signs of use, this is most likely due to the test firing.

    We do our best to clean up after test firing, but there may be some marks on the charging handle, brake, and inner components from the test firing process.

    Rest assured that your upper is considered in “brand new” condition when it is shipped out and that test firing is a necessary part of the upper completion process.

    No upper gets shipped out without being test fired and approved of first!

  • Unfortunately, the indoor shooting facility where we test fire the uppers is not long enough for proper zeroing of the optic. The optic might be pre-adjusted for our use during test firing, but the end user will need to make final adjustments.

  • While we can not provide any legal advice, the regulators are known to have constantly flip-flopped on the definition of a pistol brace and what counts as a “pistol” or a “short barrel rifle,” therefore making it extremely burdensome to provide any real definitive answer.

    The following is merely our personal opinion on the matter.

    In our opinion, the fixed position, “Fin type” brace WITH arm strap, mounted on a standard AR-type Pistol Buffer Tube, with a length of pull that is less than 10.5 inches, equipped with a strap that is both: NOT made of elastic material AND long enough to function, meets several of the requirements outlined on ATF Worksheet 4999.

    If you are unsure if your pistol build is complaint, you always have the option to simply remove the brace and other problematic accessories.

    *Nothing contained here shall be considered legal advice. This is merely our opinion. Responsibility of compliance is on the user. Just because parts are included with this kit does not imply that the kit is legal to assemble in any given jurisdiction. Always do your own research before assembling or using our upper / kit.

    *We offer the SBA3 Brace as an alternative option for those who are interested in this kit instead of the fin-type brace. Please keep in mind that the new proposed ATF rules regarding braces will need to be re-evaluated when using the SBA3 Brace. Purchase this kit at your own discretion.

  • Specifications on the size, assuming only parts used from our kit:

    • Overall Length (NOT counting muzzle brake): ~19.5 inches
    • Length counting muzzle brake: ~21.5 inches
    • Length counting Warden: ~22.5 inches
    • Recommended Gun Bag Size: 28 inches and above
    • Length of Pull (using only parts from our kit): Less than 10.5 inches
  • We recommend using this 28″ SBR / AR Pistol Bag –from Evolution Outdoor:

  • This kit includes a SLR Rifleworks Adjustable Gas Block for 5″ AR Pistols.

    This adjustable gas block works a little differently from conventional adjustable gas blocks.

    Unlike normal gas blocks where you turn a screw to slowly adjust the gas flow, this gas block comes with 3 different screws. Each screw has a different gas flow effect. So you simply install and tighten down the desired screw.

    This is more of a “set it and forget it” type of setup that shouldn’t require maintenance when you receive your upper. Based on our testing, your kit will come pre-installed with the correct screw (100% gas flow screw) for proper functionality with our Lowe Power Flat Spring and Buffer.

    However, if you chose to modify the setup or you run a suppressor, you may want to swap out the screw with a different screw, such as the -50% screw.

    The screws included are:

    • 100% Full Gas Flow

    You can purchase the -50% Gas Flow screw separately.

    Warning: If you don’t know what you are doing, we suggest that you do not touch the gas block and instead have a professional gunsmith handle this for you. You would only need to adjust the gas block if your AR is not feeding properly or not locking back on the last shot OR if you plan to run a suppressor.

  • We stand behind our product! No upper is shipped without a thorough and complete test fire and documentation.

    AR Pistols are Fun But Picky!

    AR Pistols are a lot of fun! But they also require a lot of care and initial setup to get it running right.

    Due to the extremely short gas tube, AR Pistols tend to be very picky with the type of ammo used, magazines, etc.

    We have found that the best, reliable performance has been achieved by using PMags or Hex Mags. Other brand magazines do not seem to always feed or lock back on the final shot!

    Using Our Buffer / Flat Spring is Highly Recommended

    We can not guarantee perfect functionality of your upper in every situation, however we designed this upper to pair with our flat spring and H3 (or in some cases H2) heavy buffer system which helps to make the AR pistol significantly more reliable.

    The end user may chose to use their own buffer and recoil spring setup, however you may need to fine tune the gas block if you want to achieve perfect functionality (perfect feeding and locking back on the last shot).

    What to do If You Experience a Malfunction

    If any issue arises that we determine to be the fault of our assembly or failure of the included parts, please do not hesitate to reach out to us to discuss several options such as:

    • Return
    • Troubleshooting
    • Repair
    • Replacement

    In some cases, the unit may not be functioning properly due to user error, such as improperly tuning the gas block, using the wrong buffer or buffer spring, using over pressured ammo, or having lower parts that are not compatible with the desired function.

    If the malfunction or damage is caused by faulty ammo, we suggest your best course of action to contact the ammo manufacturer as we are unable to cover any repairs due to faulty or home reloaded ammo.

    If the issue is related to any of the included accessories, such as the optic or peripheral accessories malfunctioning, you should be able to get a replacement unit directly from the manufacturer, but you can also reach out to us if you are uncertain about what to do.

    For all other inquiries or if you’re just not sure if something is working right, feel free to reach out to us here.

  • Misuse could cause serious injury or even death. Have a licensed gunsmith set up this product. We will not be held liable for any injury, damage of property, direct and/or incidental damages, loss of health, death, or any other damage as a result of using this product or included components. Small parts, choking hazard: keep out of reach of children. Not suitable for anyone under 18 years of age.

    WARNING: Cancer and Reproductive Harm – www.P65Warnings.ca.gov.

Note: 3rd party products packaged in this bundle does not imply endorsement, partnership, collaboration, or sponsorship of any kind with these 3rd party companies. All NFA / federal rules apply. Responsibility of the purchaser / user to follow all laws and regulations. 

Weight N/A
Dimensions N/A

"Naked" Upper, Complete Upper, Complete Upper + Optics Kit, Complete Upper + Optics + Brace Kit, Ultimate Kit, Ultimate Kit + SBA3