Shroud-less
The plain barreled Challenger .35/.45/.50 has a 18x1 threaded barrel, so you do not need an adapter with the right moderator.
I recommend the Emperor .357 M18x1 #S5A.
https://donnyfl.com/collections/ldc/products/2-x-10-5-inches-emperor-v3?variant=14050945073195
I recommend the Emperor .45/.50 M18x1 #S5B on both .45/.50 calibers.
https://donnyfl.com/collections/ldc/products/2-x-10-5-inches-emperor-v3?variant=14050945105963
Shrouded .357
You will need the #A91 adapter for the Challenger with a shrouded barrel.
https://donnyfl.com/products/45-50-aea-challenger-345-aea-hp-ss-max?_pos=4&_sid=63724c7d8&_ss=r
I recommend the Emperor .357 M18x1 #S5A.
https://donnyfl.com/collections/ldc/products/2-x-10-5-inches-emperor-v3?variant=14050945073195
Shrouded .45/.50
You will need the #A91 adapter for the Challenger with a shrouded barrel.
https://donnyfl.com/products/45-50-aea-challenger-345-aea-hp-ss-max?_pos=4&_sid=63724c7d8&_ss=r
I recommend the Emperor .45/.50 M18x1 #S5B on both .45/.50 calibers.
https://donnyfl.com/collections/ldc/products/2-x-10-5-inches-emperor-v3?variant=14050945105963