Loose barrel extension

[Waylander]

A manufacturer on this forum explained to me that it isn't a good idea to have a completed barrel assembly Melonite treated. He assembles Melonite barrels and extensions in separate steps. He stated that when a barrel and extension are dipped together then the salts get in between the barrel and extension leaving a cruddy buildup which is also corrosive I believe. This can lead to the extension loosening.

I'm not saying that's the case here but I would be leery of companies that offer to Melonite a completed barrel assembly or cheap barrels where the manufacturer has taken these shortcuts.

Also attempting to torque a barrel extension to the original index point isn't an easy task especially without the proper tools. There are some companies that say they can perform the service for you.

[Ned Christiansen]

I had a mfgr tell me that doing them separately caused issue, too, since the coefficient of friction is so low with mating surfaces that hard, they don't want to stay torqued. Like clamping two pieces of flat steel together so they can't move, but you've to a layer of greased, hardened steel balls between them.

At some point someone will start keying the extensions to the barrel. Or doing the Mellowtriding in such a way that the threads on both parts are masked or heck, thread after treating (yes it could be done despite the hard layer).

[Waylander]

Another method involves installing the extension and Meloniting the assembly, removing the extension, cleaning the threads then reinstalling the extension. This way the threads aren't treated. The gas port is then drilled so it will be indexed properly with the extension.

[T2C]

I had a mfgr tell me that doing them separately caused issue, too, since the coefficient of friction is so low with mating surfaces that hard, they don't want to stay torqued. Like clamping two pieces of flat steel together so they can't move, but you've to a layer of greased, hardened steel balls between them.

At some point someone will start keying the extensions to the barrel. Or doing the Mellowtriding in such a way that the threads on both parts are masked or heck, thread after treating (yes it could be done despite the hard layer).

Would it be easier to chase the threads after treating the metal?

[GH41]

Would it be easier to chase the threads after treating the metal?

I wouldn't want to buy the tooling to do it besides chasing an existing thread isn't easy. It's not like you can just skim cut the treatment off of the threads. I doubt you could even take a half thou off of a treated part. The treatment changes the metal's structure. Melonite is not a coating. There is a reason ADCO and others won't work on these treated components.