Is a shotgun louder than a rifle or pistol?

[hso]

None of this takes into account that you are 24+ inches further away from the muzzle of the shot gun.

Sound pressure levels for firearms are typically taken at the shooter's position for these charts so this isn't the case. Remember that a firearm sound suppressor reduces the SPL by allowing the gasses to expand and loose energy before exiting the firearm/suppressor system. A longer barrel provides some of the same benefit.

The frequency measured is centered on the human hearing range since that is all we're interested in.

Note that SPLs are logarithmic and that you can consider the pressure as doubling for each 5 dB increase.

NEVER shoot without hearing protection and double up with muffs and at least NRR 30 plugs.

 

[lizziedog1]

Many years ago I was at a rifle range. It was the outdoor type. A guy was shooting a 50 caliber Desert Eagle. He asked if I would like to try it. Of course I did.

My wife stood a few feet behind me when I shot it. She swore to me that she could feel some sort of shock wave hit her everytime I touched a round off. She said it felt different then other guns.

 

[Balrog]

Why do my ears ring when I shoot a 45 or 9mm, but don't ring when I am quail hunting with a 12 or 20 gauge?

 

[GLOOB]

So what's louder, to the shooter. A .223 with a flash hider (not muzzle brake)? Or a ported 12 gauge with 28" barrel?

How bout to the other guys on the line?

 

[hermannr]

Being old and very hard of hearing..never shoot anything (except maybe a suppressed .22) without hearing protection...ever...if at all possible!

Anything over 1100fps will give you a supersonic crack. Compaired to the actual weapon firing, this really is not the main source of the sound. The main source is the expanding gasses from the burning powder the "pressure wave" these gasses create.

Two things with your hearing, and damage. The peak pressure, and the duration of that pressure. The longer the pressure wave is over 85db (or 115db in other views) damage will occure, whether you think so or not.

In an SD situation in a house I would much rather hear a .38 or a 45 with a big slow bullet, then say my 7.62X25...while the supersonic "crack" isn't the main source of the sound pressure wave, it does add to it.

I light load in a shotgun would do the same. I would not want to fire a full 3" load inside a building.

 

[Justin]

When judging the amount of noise generated by any of these guns, refer to a dB measurement chart.

Also, keep in mind that Decibel measurements are logarithmic, and when looking at measurements, an increase of 3 dB correlates to a doubling of the sound pressure.

 

[brickeyee]

Most of theh SPLs for guns are at best approximate.

The impulsive nature of the sound makes it very difficult to measure values reliably.

The equipment rarely has enough bandwidth (and adequate response speed) to deal with the Mach wave produced.

 

[hso]

Why do my ears ring when I shoot a 45 or 9mm, but don't ring when I am quail hunting with a 12 or 20 gauge?

When you're hunting do you fire 50+ rounds? I bet that when you're shooting 9mm that you're shooting a box or two.

 

[benEzra]

Muzzle brakes and flash suppressors deflect the sound rearward, so even though the decibel level is the same, more of the blast and noise comes back at the shooter. What's even worse, is the guy next to you on the range is shooting a large calibre rifle with a muzzle brake, that really blasts the people on the sides.

That is true of brakes, but is not generally true of flash suppressors. Good flash suppressors tend to direct the blast downrange away from the shooter, resulting in less blast from the shooter's perspective, not more.

It's certainly subjective, but IMO a 16" .223 with a Vortex FS is more pleasant to shoot than a 16" .223 with a bare target muzzle.

Excellent information. However the one thing not pointed out was the frequency of the sound wave. If you listen to a 357, while the DB level is loud the sound wave will have a wider wave form and not be precieved as loud as for example a 223 round with a shorter wave form.
Think of the ocean= a nice smooth rolling waves = 357
Think of the ocean = sharp white tips waves coming in very fast = 223

The dBA scale corrects for the frequency response of the human ear, and a .357 revolver is considerably louder in dBA than a 16" to 18" unbraked .223.

A 16" .223 at the muzzle is probably venting at 3,000 psi or less; a .357 at the barrel-cylinder gap is venting at more than 30,000 psi, and may actually be higher pressure at the muzzle as well (depending on barrel length).

a shotgun, running at low pressure with a fairly long barrel will be on par or quieter than most pistols, but not anywhere near a rifle of equivalent barrel length.

Measured dBA put defensive-length shotguns (18" to 22") very close to 9mm/.40/.45 pistols and .223/7.62x39mm/.30-30 rifles, though adding longer barrels to any of the above will reduce their peak loudness some.

You are right that a shotgun runs at a lower chamber pressure than a rifle, but remember that a .729" 12-gauge bore has more than ten times the cross-sectional area of a .224" AR-15 bore; in terms of sound production, that big increase in gas volume more than makes up for the reduced pressure at muzzle vent. The result is that sound levels are pretty comparable among most defensive shotguns, carbines, and pistols.

 

[The Wiry Irishman]

You are right that a shotgun runs at a lower chamber pressure than a rifle, but remember that a .729" 12-gauge bore has more than ten times the cross-sectional area of a .224" AR-15 bore; in terms of sound production, that big increase in gas volume more than makes up for the reduced pressure at muzzle vent. The result is that sound levels are pretty comparable among most defensive shotguns, carbines, and pistols.

The gas volume question was something I've been thinking about since I posted, especially after I re-read the thread and saw your earlier post about it. After all, sound is a form of force, force is mass times acceleration, pressure level governs acceleration, and by distilling it down to just pressure like I did you lose the entire mass part of the equation.

Something else I've been wondering about is, powder volume aside, the effect bore diameter would have on sound, both in volume and tone. Volume-wise, would a larger bore be quieter than a smaller one, since the gas would be expanding from a larger area? Or would the magnitude of the pressures involved compared to the relatively small differences in area make it more or less a moot point? Also, am I correct that a larger bore diameter would result in a longer wave form and therefore a lower (tone-wise) sounding report? I'd love to hear someone with more than my basic mechanical physics background expound on this.

Overall, though, this discussion is completely academic, because and unsupressed firearm will be many, many decibels into the permanent hearing damage range. How loud your gun is shouldn't be even a secondary factor in how you choose a defensive firearm.

 

[Sunray]

Any sound over 85 decibels is enough to cause permanent hearing loss. And it's accumlative. Every gun shot, even a .22 LR, is enough. So what cartridge is the loudest is irrelevant.

 

[Oddbod]

I fired around a dozen shots at pigeons with the 12ga this evening with no hearing protection but I wouldn't want to fire the same number of shots from the .270 without hearing protection.
Maybe it's personal perception but the .270 seems a LOT louder.