1/2 20 x 1/2 20 adapter

I think you want a 1/2 UNF barrel extender/barrel extension. Tighten it into place once, then you can spin your moderator on and off without changing barrel tension.

Found one on fleabay:

https://www.ebay.com/itm/173200775201

Don't know whether Donny makes one, but you could ask.

barrel extender.1651190625.jpg

 
I think you want a 1/2 UNF barrel extender/barrel extension. Tighten it into place once, then you can spin your moderator on and off without changing barrel tension.

Found one on fleabay:

https://www.ebay.com/itm/173200775201

Don't know whether Donny makes one, but you could ask.

barrel extender.1651190625.jpg

I send Donny an email still waiting for reply that would be ideal to get got from him. 
 
Anyone know where I can get a 1/2 20 x 1/2 20 unf. I wan to tension my maverick like Ernest showed on YouTube but want to be able to take my moderator on and off with out losing tension.

Not sure if you saw this thread I posted a while back. I posted it in the PCP tuning subforum. Not sure if this is exactly what you are looking for. I designed it around a Taipan Vet, but will work on other rifles.

https://www.airgunnation.com/topic/30mm-threaded-shroud-extension/?referrer=1

I had contacted the machinist at Donny FL and he told me about $62 for his. Mine are going to be about $32 plus shipping.