Bad Attitude Department Complete AR15 Upper - 4.75" 5.56x45

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Only 4.75"???  Thats not practical!!!!!

Well, no it isn't, but it sure is fun.  I've never met anyone who shot this and said they were bored.  This is an epic little noise maker and will brighten any range day, literally.  You can probably light a cigarette three lanes over from the muzzle flash alone.

Looking for extreme accuracy?  This ain't the upper for you.  Can you hit a IPSC sized steel target at 100 yards?  Yes you can.

We build these to eat any commercially manufactured ammo you feed them.  They don't care if it is high dollar US produced 5.56 NATO or the cheapest Romanian steel case you can find.  It will function with all of it. 

With 5.56 NATO M193 it's gassy on a carbine buffer.  We'd reccoment an H2 if that's what you are shooting.  If you are blasting cheap imported steel case, a standard carbine buffer will probably do well. 

In reality our uppers are extremely well built with attention to detail paid to every step of the process.  We use only components that we are familiar with and have been using to great sucess for years.  We inspect and prep every part prior to assembly, then test fire and confirm accuracy with each unit. 

  • 4.75" 5.56 NATO 1:7 nitride treated barrel
    • Chamber honed to improve reliability
    • Feedramps polished
    • Gas port pin gaged at .062" for optimal function with all types of ammunition
    • Bore and chamber inspected for defects and burrs
    • Headspace checked with PT&G go and no-go gages
  • Azimuth precision ground BCG with 9310 bolt and billet extractor
  • Aero Precision 4.8" Atlas R-One MLOK handguard
  • Milspec forged upper receiver - hard coat anodized
  • Set screw gas block checked for fit and secured by set screw in dimple
  • Charging handle with extended latch
  • M249 SAW style flash hider


We test these with commercially produced 5.56 NATO loads and recommend you use only name brand new manufacture 5.56x45 ammunition.  You are welcome to use cheap steel case if you wish, but you will see a decrease in barrel life and reliability.  It won't void your warranty.   We will not warranty any issues arrising from the use of reloaded or commercially remanufactured ammunition. 

This upper is to be used on pistols or registed short barreled rifles only.  All NFA regulations apply.

Current Promotion:  for each upper you order, we will also include a Bad Attitude basic lower parts kit (no FCG, no grip, no trigger guard) and a Bad Attitude lower receiver of our choice.  The lower may be a slight blem or a perfect lower.  No choice of model or design. 

Have your transferring dealer email a copy of their FFL to

Product Reviews

Score: 5 out of 5 (based on 2 ratings)
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4.75” Upper
Written by Justin on 26th Dec 2023

Just got my upper and couldn’t be happier! Polished feed ramps incredible build quality. No wobble on the upper and came with a parts kit and lower. No better buy around! Buy with confidence!

4.75” 5.56 Bad attitude dept. upper
Written by John Kozak on 23rd Nov 2022

I was a little hesitant to order at first but I am very glad I did I received my upper receiver in about a weeks time and couldn’t be more pleased with my purchase. It fits my lower nice and tight with no play or jiggle at all. Also the assembly is top notch no dings or scratches anywhere polish job on feed ramps is really nice and the parts used are of very good quality best assembled upper I have ever purchased online. If you are building a micro ar pistol you need this!!