Hollywood gun with silencer sound- accurate?

You know the generic sound they put into movies when somebody fires a gun with the the hollywood generic screw on the front of your barrell silencer?
The muffled half “chirp”.
Is that an accurate representation of how it sounds or is that just a sound effect that has become staple?

No, it’s not accurate.
I’ve fire a suppressed 9mm. and it was still quite loud, like a firecracker. (It did need new wipes, though).

I’ve fired a .22 rifle with supressor (perfectly legal to possess in the UK without additional paperwork beyond the normal FAC) and almost all you could hear was the sounds of the action and the lead hitting the tin cans at the bottom of the garden. It was quite cool.

Hampshire

No, that’s just Hollywood. There’s a lot that goes into silencing a weapon, especially something more powerful than a .22. You’ve got 3 sounds that you have to muffle; the first and most obvious is the blast from the expanding gases. You can do this with a suppressor of some sort that works on principles like a car muffler, it allows the hot gases to cool and expand slowly so you don’t get the big boom. Effective silencers for larger calibers tend to be pretty bulky items.

The next item is the sonic boom of the slug. If your bullet is travelling at more than 344 meters/sec you will have a sonic boom. To reduce this you need to use subsonic ammunition. A 22 short is subsonic and IIRC, a 9 X 19 mm is also subsonic. Last and least, you have to get rid of the noise of the action. The slide slamming back and firth makes a good deal of noise. Of course, some kind of single-shot or bolt action would probably work very well.

Hope this helps.

Testy

Minor nitpick, 9X19 is frequently supersonic (although subsonic rounds do exist) but .45 ACP and .38 Special are generally subsonic.

Bobo**

Thanks for that. I just grabbed it off the 'net. I should have checked further.

Regards

Testy

I’ve read that silencers on handguns aren’t those slim cigar-shaped cynlinders that you just screw onto the barrel like you see in the movies. To adequately muffle sound, the silencer needs about the same dimensions as a 2-liter soda bottle, or so they say.

Johnny

Yeah, something close to that. For sure, James Bond isn’t going to have one tucked away in his suit somewhere.

Testy

How loud is a bullet’s sonic boom? Obviously depends on the bullet, but are we talking something that would be noticeable from a distance?

jk1245

I’m not sure how to answer that. Not that it’s a dumb question or anything, there are just so many variables. You could hear it across a room but maybe not is you were outside.

Regards

testy

I generally feel like an ass mentioning minor stuff like that, it’s not even really relevant to the discussion… And the 9mm isn’t much above the speed of sound (which is variable depending on the atmospheric conditions, IIRC).

Is an actual 2 liter soda bottle an effective silencer? This was used in The Departed.

Bobo

There’s something I hadn’t thought about. What determines the sound pressure level of a sonic boom? Would a 9mm traveling just slightly over Mach 1 make only a tiny sonic boom? If something travels at Mach 2, does it make twice the amount of noise? Or does it only vary by the size of the object? No idea where to look this up.

Regards

Testy

Departed

No idea. I’d expect the gas pressure to either shred the bottle or blow it off the muzzle. Maybe .22 or the like.

Testy

Yup. I saw this demonstrated flawlessly. On “CSI”

Yeah? That is slick. What kind of firearm/caliber were they using?

Thanks

Testy

Not true. There are modern silencers that are fairly compact; not as tiny as some of the things you see in movies (which are somehow affixed to the barrel that isn’t threaded or exposed for set screws) but that are smaller than a soda can. Here is a suppressor that fits onto an AR-15-type rifle or carbine firing the 5.56mm NATO round; it’s about as large as a medium sized C-cell Maglite without the head.

As for the sound of a silenced shot, it depends on the silencer–some make barely more noise than a whisper (although the mechanical sound of the action cycling is distinctive) and some make a dull thump with a zipping noise like a coin run over the teeth of a comb. But not one that I’ve ever heard sounds anything like they do in the movies, and for that matter, gunfire in real life sounds almost nothing like the sound effects foley artists use to indicate gunfire.

Not only will this not work effectively for anything much larger than a .22LR, it’s also illegal to possess an unlicensed silencer without the requiste ATFE stamp and whatever state code restrictions apply. This is a federal felony crime, even for an improvised device. Please don’t extend the discussion on this, as the mods will almost certainly lock the thread for discussing an illegal activity.

Stranger

Based on little more than conjecture and supposition, it’s my understanding that the size (or maybe “size and shape”) of the object will change the sound more than speed.
I can visualize it, but I don’t know that I can write it… the “boom” is caused as the object travels faster than the sound waves can get out of the way, so they compress and sound like one. If somethings going mach 17, the sound still travels at the same speed and may … get packed tighter? … but won’t get louder because they’re still going the same speed…

No, that sucked. We need someone who understands it well enough to explain it. Sorry.

It’s not that hard to get a legal silencer. BATF makes big frowny faces about improvised and/or unlicensed suppressors. It’s about the same as modifying a semi to a full auto. Bad ju-ju’s.
(and it doesn’t work very well, or so I’ve heard)
On preview, what Stranger said

Stranger

Thank you. That thing’s amazing. I’ve never heard of anything effective that is so small. The things I’ve bumped into in the past, especially for rifles, were more like a car muffler stuck on the barrel.

Thanks again

Testy

Bobo

Hmmmm. I think we need a serious physics guy for this one. I’d think that packing the compressions/rarifications tighter would increase the frequency.

Yeah, the various law enforcement people take a dim view of homemade silencers. I had no idea you could actually buy one of these things without being in the police/military. Maybe someday. I have a friend from IIRC Finland where silencers are not only legal, they’re recommended, to avoid bothering people with loud noises. He sits on his back porch and shoots at tin cans and the like. :smiley:

Regards

testy