You will need this adapter for the Terminator .357
https://donnyfl.com/products/aea-terminator-m18x1-big-bore-adapter?_pos=1&_sid=07cdcdb36&_ss=r
I recommend the Emperor .357 M18x1 #S5A.
https://donnyfl.com/collections/ldc/products/2-x-10-5-inches-emperor-v3?variant=14050945073195
The .30 cal Terminator 2 uses the same adapter as the bigger .357 model.
https://donnyfl.com/products/aea-terminator-m18x1-big-bore-adapter?_pos=1&_sid=07cdcdb36&_ss=r
So when you order a moderator you should get the#S18, .25/30 cal Ronin, but put in the notes that you need a M18X1 endcap instead of the standard 1/2x20 UNF thread one.
https://donnyfl.com/collections/ldc/products/2-x-6-5-inch-ronin?variant=41534539652