Can a threaded barrel be unthreaded

It does not /literally/ prohibit it. There is significant discussion as to whether the wording does mean that, and again I can't find anybody who's been in the slightest hint of actual trouble over it.

This thread (from another sub so use care) has a lot of people who are quite familiar with the laws going over it, back and forth:

https://www.tforum.com/r/WAGuns/s/HIu5CQNoVs

Would just marring the fuck out of them with an angle grinder be enough? That’s probably the cheapest option

Hit it with a blowtorch and unscrew with some vice grips. Red loctite just has to be really hot to give up.

idk... file the grooves down until they won't thread?

I'm sure s competent gunsmith/machinist could do it, but it might me cheaper to replace the barrel. This is also depressing; when's the last time threads hurt anyone?

I got a nut breaker, which worked just as well. And it was easy to come by the not California muzzle device adaptor.

Some states use serial numbers to permit certain model. You need to confirm how/if converting it to non threaded barrel would be validated or allowed.

Yeah this would probably be ideal!

There is such a thing and it is normally applied to a loaded mag in the vicinity of a gun for someone to be charged with the constructive possession of a "loaded" firearm. It could theoretically apply to a barrel or other prohibited feature and probably has in assault weapon ban states.

I dont want to test a prosecutor's discretion or a state's unsettled case law ... I'd keep my threaded barrel in the state it is legal to avoid any issues lol.

JB Weld, black spray paint.