Kind of depends to me but they are LOUD!!!
One of the newer 416 SMLs shooting a 340-375gr bullet in the 3000fps+ range would be brutal without a brake. Performance exceeds that of the .416 Weatherby magnum cartridge with 119gr of Retumbo and a 450gr.
My 45 is not that bad but i dont push it either. I could approach 3000fps with a 275gr if i really wanted but i have no need to try it.