Suppressor thread question

[longshot]

Hi all.
I have just had a new barrel fitted to a rifle and the muzzle is threaded 1/2x20 for an over barrel DPT suppressor.

When I try to screw on the suppressor it is difficult to get the thread started and then it feels like it will gall up after about 3-4 turns.
I have tried a few rimfire suppressors for fit too, one feels like galling up, the other which must have a courser thread goes on.
The thread protector that came with the new barrel screws onto a couple of other 1/2x20 threaded barrels without any issues.


I plan to contact the outfit who did the work on Monday but thought I might be able to see what my options are in the mean time in order to help inform Mondays discussion.
Ultimately this is not at all about who is at fault or naming or shaming, it is about achieving an end result of being able to fit a suppressor to the rifle, hopefully without having to send it back again as the outfit is not local.

The simple option of chop and re-thread doesn't exist either as the barrel is just long enough for the over barrel DPT to not contact the forend.
My preferred approach would be just to get a new DPT suppressor that hasn't had a muzzle thread cut and have it tapped out to the same thread as the rifle barrel.

My question to the Forum is;
Is this practical from a perspective of would the thread protector have been threaded with a tapping bit in which case the same bit could be used to tap out the DPT to the same thread, or would the thread protector thread have been cut on a lathe (in which case could the same thread be duplicated inside an overbarrel DPT?)

Or am I over thinking it and is there a much easier way? Open to suggestions on that one....
thanks in advance for the input.