Donny FL - Which Thread size for the Wildcat MK3?

So I just got my Mark 3 .22 sniper and I chose to get a 30 cal Donnie FL because I want to get a 30 cal Barrel kit sometime soon. And you need an adapter because the 30 cal is larger I'm not sure what that thread is but Jim at Precision airguns gave me an adapter that went from the 1/2 20 UNF up to whatever the 30cal is. and by the way it is just as quiet as my daystate Huntsman shooting the same velocity even with that larger 30 caliber hole
 
https://utahairguns.com/donnyfl-fx-impact-wildcat-1-2-x-20-unf-adapter/

I just came across that website today at Utah Airguns and it states: 

"This adapter is for Impacts and .177/ .22 Wildcats that have the M20x1 male threaded end. It will screw onto your factory shroud and allow you to screw on an LDC with a 1/2 x 20 UNF Female threads."

So, for those who have older model Wildcats or Impacts that have M20x1 and want to upgrade to 1/2 x 20, this adapter is probably a good option. 

I'm planning on buying my Wildcat Mk3 from Utah Airguns. If anyone has any other suggestions, please let me know. Also, Huggett vs. DonnyFL; any opinions on which one is quieter? I know the tighter the clearances, the quieter they become:

https://www.youtube.com/watch?v=JhQOLlWP4PU