Should personal protection ammo be subsonic?

[Z_Infidel]

That list shows .44Spl as one of the least loud, and I have some hearing damage and mild tinnitus in my left ear from an incident several years ago when a .44Spl revolver was fired when I wasn't wearing hearing protection. And that was outdoors.

I'm very surprised to see .38Spl rated louder than .44Spl.

 

[Kreyzhorse]

I'll carry what I feel works best in a SD situation. I'll worry about my hearing after the fact.

And for the record, I agree that there likely isn't much difference between a sub sonic and super sonic blast.

 

[w_houle]

Wanted to store my BP .44 for the winter, so I went to my range to shoot it. I forgot my ear plugs... meh, it's only black powder and five rounds So needless to say after the first round went off, I went back to the house for ear plugs.
Oddly enough, it's the same BP revolver I used to tame a raccoon that found it's way into my trailer. No ill effects on hearing, although I found out that two shots from a BP will fill a room with smoke rather quickly

 

[JohnKSa]

...Also, do you think the muzzle blast is equally severe at all points of the compass relative to the weapon, or would it be reduced behind the weapon? What about the sonic boom?

DIRECTLY behind the weapon the blast tends to cancel out but the cancellation area is very small. This is why right-handed rifle shooters are often more deaf in their left ear than their right.

My gut feel is that indoors the sonic boom and the blast will reflect off of walls and other hard objects which will tend to even out the discharge noise and eliminate the tiny cancellation area. It will be pretty loud everywhere.

One thing that tends to get glossed over in these discussions is the fact that the attacker won't have chosen his gun for how safe it is for your hearing and his muzzle will be pointed in your general direction. One could argue that the best thing for one's hearing is to stop the attacker from shooting as rapidly as possible. That would make the most effective firearm the best choice for preserving your hearing. Doesn't hurt that it's also the best choice for preserving your life.

Then we get into what's the most effective choice...

 

[shooter_from_show-me]

My gut feel is that indoors the sonic boom and the blast will reflect off of walls and other hard objects which will tend to even out the discharge noise and eliminate the tiny cancellation area. It will be pretty loud everywhere

You are correct! Went to the indoor range last weekend and brought my XD9 and a Colt Woodsman 22LR. I shot about 6 rounds of .22LR before I decided it was time to put the plugs back in the ears! VERY noticable between outdoors and indoors thats for sure.

 

[benEzra]

Barrel length, presence or absence of a barrel-cylinder gap, and bore diameter all affect sound amplitude considerably more than the velocity of the projectile does.

For example, a short-barreled .357 is several dB louder than a 16" barreled .223 Remington, even though the .223 bullet is pushing Mach 3.

I have felt nothing like the same ear-splitting crack when shooting next to others shooting 45s and even .44 mags. Maybe the .357 in a snubnose is a particularly bad combination for ear damage.

My experience is similar. The reason that it is SOOOO loud is (1) high pressure cartridge, (2) 35,000psi gas venting laterally from the barrel-cylinder gap, and (3) super-short barrel.

It's not the bullet velocity that makes it so loud---plenty of .22LR rifle loads exceed the velocity of a full-house 125gr .357 out of a 2" barrel, generally around 1250 fps---it's the pressure differential between the escaping gases and the air, which is arguably greater for a 2" .357 than almost any other firearm, at least until somebody makes a .44 magnum or .454 Casull snubby.

BTW, to get a feel for the barrel-cylinder-gap noise, if you have ever experienced the ears-plitting shriek/hiss of high pressure compressed air escaping at high flow rates through a valve, or a high-pressure gas cylinder (typically 1000-3000 psi) dumping pressure, imagine what it would sound like dumping 35,000 psi through an annular slit. That's why revolvers are louder than fixed-chamber firearms of similar caliber, because you're getting more than just the muzzle blast.

Here is an actual Schlieren photo of the blast waves produced by someone firing a revolver (I think a .357):

http://www.hightech-edge.com/explos...shockwave-images-high-speed-videography/1684/

Note that the initial shockwave bubble is centered on the barrel-cylinder gap, and that the shockwave from the supersonic bullet is much smaller and weaker, and is traveling away from the shooter so that it does not significantly affect the overpressure at the shooter's ears. Also note that the bullet is already outrunning the sound from the barrel-cylinder gap and the muzzle venting.

Just for comparison, here's an AK:

Note that the bullet's supersonic Mach wave is traveling away from the shooter and doesn't contribute much to the sound the shooter hears.

http://www.nytimes.com/slideshow/2008/10/27/science/102808-Cough_index.html

 

[Jkwas]

That's really good photography, and quite an education. So it's not so much the speed of the bullet, but the force and location of the burning gases and type of firearm used.