You can own a 7.5 inch upper receiver legally. If you assemble it as a pistol and it is legal for you to possess in your state it's fine. If you put a rifle lower on it you need a tax stamp.

2 ways 1st is NFA tax stamp the 2nd is if it is a AR pistol

Yes, in a "Pistol" configuration with a "Stabilizer" brace such as a KAK or Sig Brace and not a "Standard Shoulder Stock". Add a shoulder stock and you need an NFA Tax Stamp/Registration as it would then be classified as an "SBR" Short Barreled Rifle".

2 ways 1st is NFA tax stamp the 2nd is if it is a AR pistol

Please click the green box stating it as the best answer. We are
rated on our answers and are just volunteers, not Buds
employees. You can choose more then one Thank you!

No not without a tax stamp