Q&A for AR57 ULT 12in Barrel 5.7x28mm Upper Receiver Assembly

Q

Boss, guest, from MI, United States, asked on March 19, 2026

Is this a complete upper receiver?

A

Answered by mark, member, from MI, United States, on May 14, 2026

Yes, just keep in mind. The magazine is not included.

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Q

Kevin, member, from PA, United States, asked on October 16, 2025

Does come with a BCG?

A

Answered by mark, member, from MI, United States, on May 14, 2026

Yes it does.

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Q

Gunsmoke, guest, from CT, United States, asked on November 27, 2024

Is the length of the 12" barrel include the muzzle brake or is it a 12" barrel + whatever length of the muzzle brake?

A

Answered by J, member, from TX, United States, on June 05, 2025

12" barrel...from the chamber to the end of those threads.

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Q

Bill, member, from VA, United States, asked on December 08, 2023

Does the 12" barrel Upper require an NFA Tax Stamp if you mount it on a standard AR15 Lower?

A

Answered by J, member, from TX, United States, on June 05, 2025

If you have a standard buffer tube and standard buttstock attached to that standard AR lower...then yes, of course...that's a silly question.

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Q

T. Andrews, member, from MD, United States, asked on October 26, 2023

Do PS 90 magazines fit ??

Expert Answer

A

Answered by Ethan, Gear Expert, from IL, United States, on October 30, 2023

The AR57 ULT 12in Barrel 5.7x28mm Upper Receiver Assembly can be used with PS-90 magazines, however, the best mags to use with this upper are AR57 brand P90 pattern mags as there are slight differences between the AR57 and FN brand magazines.

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Q

Brenden Koski, member, from MI, United States, asked on July 28, 2026

Can you run an FRT with this upper receiver?

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Q

mark, member, from MI, United States, asked on May 14, 2026

What weight is the buffer that comes with it?

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Q

Phillip Ferris, member, from SC, United States, asked on March 20, 2026

Can I make this bufferless?

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Q

Jay, member, from OR, United States, asked on November 20, 2025

Why is my bolt carrier milled so much trigger wont engage? Also firing pin doesn't push out far enough to hit the round ?

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Q

james, guest, from GA, United States, asked on February 09, 2024

Full auto bolt ? Will it work in a registered full auto lower ?

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Q&A for AR57 ULT 12in Barrel 5.7x28mm Upper Receiver Assembly — 12 Questions & 5 Answers