Silencer threads

[Beetroot]

1/2 by 20 would be most common on rimfires and reasonably common in centre fires.
Hard thing with centrefires in depends on barrel width to what thead places like DPT will do, then different manufacturers do different threads depending of its for American or European market.

Correct me if im wrong, but I believe the Tikka CTR has an imperial thread and the Tactical a metric one.