As @Tommy said does it revert with the can off to tight again (relatively). I had this issue with a hardy gen 4 can on t3 7 rm when I ran it in with federal blue 150s groupings got worse - the load had a High degree of carbon in it and was causing actual carbon dags on the internals. Sent everything to Hardys for them to concur the approach was the suppressor and take everything else out of the equation. The gun was off to fiordland in 3 weeks at the time and I didn't want to fuck around.
Dan looked at him himself and agreed with the issue was the buildup in the internal baffles re bored it slightly wider came back and was shooting less than a half MOA.
Don't know if this is you're issue but thought I'd share my experience.
Sorry about the edits bloody iPad after a few whiskeys is murder...
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