A salami spec 30 Nosler is only 3.34 coal, I was to have a chamber cut for 3.6 coal with .225 freebore.
Only thing may try to do is recut my chamber to a SAAMI spec 300 ultra mag. I don't even know if that's possible. I am still learning everyday.
just because you have a longer free bore does not mean you can't shoot off the shelf ammo. In fact in this instance I would recommend you go buy some and see what it does.
Freebore does not independently dictate COAL, bullet shape has just as much if not more to do with it. There can be issue running a long bullet in a short throated chamber but no problem to run a short bullet in a long throat
I think you have some learning to do about reloading and load development. Is there someone in your area that can teach you a bit. There is a ton of great videos on you tube also.
I would not re-chamber the rifle unless you diagnose it to be a bad chamber job.