I met a guy a along time ago was the biggest poucher I have ever heard of. he claimed his main gun of choice was a 30 carbine with the action pined so it would only shoot one shot at a time and a supressor he told me it was quieter than his pellet gun. I never saw the gun and wanted little to do with him he was a real scary outlaw drug smuggler type
I am not a big 30 carbine fan except for plinking and the ammo is to pricey for that. I bought one 20 years ago at a show bluesky imported or some thing like that $75. found it useless eccept for a saddel gun an pack in trips. Not trying to say its a bad idea would be cool but not one I would put high on the list. You would likely have to add some freebore for that longer bullet not sure. Why not do a 300 wisper??. it can go subsonic and is a pretty good round with lighter bullets loaded up hotter.
A suppressor may be the next big Item I buy if I ever get any extra cash.