There’s a taper, almost like pipe thread, and virtually no thread relief…a spacer won’t screw all the way down to the shoulder of the barrel.Some rifles with 1/2 X 28 thread pitch have the threads .600 inch deep. Most rimfire rifles and suppressors are only threaded .400 inch deep.
You can get a spacer that threads on and keeps your suppressor in line so you don't get baffle strikes.
I have one that I have to use on a couple rifles.
If you like the way it shoots, a spacer is a lot cheaper than a new barrel. Now if you want a new barrel for other reasons, I won't talk you out of it.
The problem is ‘deeply rooted’ in that there’s no relief, the treads are terrible, AND there aren’t enough of them to space and have enough left to screw a can on….basically ruined the f’n barrel to my notion.If you turn out some of the spacers thread, it will screw down flush