Re: Wondering about Max cal size for hunting.
Caliber has some effect on the amount of noise, but is not really the cause. Rather it is the burning and expanding gases from the ingition/combustion process that ends up disturbing the air to cause the report. Basically, the more powder/gases that are burning out of the barrel, the more noise and flash it will produce. If a case is designed to achieve a complete powder burn in a given barrel length, shortening the barrel will increase the flash and noise as a result of powder burning and gases expanding out of the muzzle. This is why suppressors are needed, they are designed to trap the expanding gases and allow them to finish their burn and cool before escaping the muzzle..
As a rule of thumb the larger the case the more powder is burning and the shorter the barrel the more flash and report you will get. Overbore cases like some of the belted magnums etc will produce more noise over a smaller more efficient case.
eta: all guns are going to cause hearing damage. Hearing protection attempts to reduce the amount of damage done. A +130dB report from a braked rifle, with -30dB NRR earmuffs, is still +100dB of noise. The NRR ratings are misleading as well, they are rated for continuous sound and not impulse type noise as generated from gunfire. So even with earmuffs or plugs with a good rating, (like -33dB)you are still exposing your ears to approximately +100dB of noise in one quick blast as opposed to the constant rumbling of a jet takeoff in your vicinity. Someone put it best when they said 'hearing damage is cumulative and permanent"
pps I shoot an unbraked .300WM with a 26" barrel wearing earmuffs and it is still loud as hell.