Are barrel nuts specific to the handguards used?

Can I swap out a handguard from another manufacturer without needing to mess with the barrel nut? I want to put my heavy barreled upper on a diet.

I'm ignorant about some things, and this is one of them. Now, if you need a Quadrajet rebuilt, and set up for racing, THAT I can do while napping.

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NRA RSO

Not certain what AR platform you are looking to modify, but if you have the usual handguard attachment configuration (not a free floated barrel handguard arrangement) you should be able to switch to most any Magpul, Colt, Stag, etc. handguard appropriate for your rifle's barrel length.

Post a photo of your current handguard and upper receiver/barrel and it will be possible to give you a more definitive answer.

It's a free-floating quad rail.

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NRA RSO

If the quad rail screws directly into your upper receiver, it most likely replaced your barrel nut, spring weld, lower handguard retaining ring, etc. So, you probably would need to source all those parts to retrofit a standard handguard, and that's after you strip the barrel to the point where you can remove the current parts and install the new parts.

Some are specific to one another. And some of those even require a proprietary wrench.

The "Generic" Barrell nut for an AR would be the USGI one. It was designed for non-free float handguards but there are some free float handguards (DD Omegas) that work with it. Othe free floats (Centurion) require cutting away the delta ring.

Most free float hand guards I've dealt with would use a vendor or model specific barrel nuts.

If you can say what make and model handguard you have and what you are looking to buy, that would enable better advice.