Is a "Quiet" Caliber Physically Possible?

[Dionysusigma]

Merely just musing on a thought I had this evening after a long day of wearing ear plugs. Could there be a way to make cartridges, without the use of a deadening system, any quieter than they already are?

NOTE: BEFORE I GO ANY FURTHER, IT IS NOT MY INTENTION TO CIRCUMVENT ANY LAWS, NOR FIND ANY LOOPHOLES TO GET AROUND OWNERSHIP OF SUPPRESSORS. THIS IS MERELY HYPOTHETICAL.

Some of the same lines of thought also used in this thread: http://www.thehighroad.org/showthread.php?t=80956

I am growing quickly tired of wearing earplugs for 8 hours straight (although the alternative, having my hearing destroyed by jet engines, is much worse). I really don't want a gigantic, silly-looking cylinder hanging off the barrel of my rifle. I want, even less, to pay an extra $200 and waiting a few months for something that'll only reduce the decibel level by 10 or so (and thus still necessitating the use of wearable hearing protection) anyway.

Is the loud noise from firearms simply necessary to achieve the performance they offer?

The only alternatives I can think of would be either a rail-gun system (still moot if the projectile goes supersonic, and from the sound of discharging a capacitor), or electronic sound suppression (taking the sound-wave-form generated by the gunshot and inverting it). Thing is, you'd have to have a really fast processor to be able to do it in time. Fast enough that it doesn't exist in an economically feasible form yet. And even then, it would probably still count as a suppressor, subject to either a $200 tax or 5-10 years (like the infamous beverage bottle adapter).

So what about alternative propellants? Alternative materials for bullets?

Or am I just asking too much of the laws of physics?

P.S. If one were to fire a gun (presumably while wearing a space suit, and an AK, because they will work in any environment ) in empty space, would you hear the shot? Considering that the powder, when burned, changes into expanding gases, wouldn't the blast actually make a "noise" when the gases reached your helmet? And, would gas-operated weapons work the same while in space?

 

[funfaler]

22CBs are very quiet, out of a long gun. They are sub-sonic.

Not a real rifle, but still quiet enough to shoot with out plugs, in a long gun.

Just make a giant 22CB, in a 30 cal or so

 

[American_Pit_Bull]

My suppressor reduces the sound by over 30 dB....

And no, you would not hear a gunshot in space because of the lack of air molecules which carry the sound.

And as far as a gas operated firearm being able to cycle... Yes it would, since the gas is contained in the cartridge and has nothing to do with the atmosphere.

 

[Sav .250]

For every action there is a ...re-action. Good luck on your quest.

 

[TCB in TN]

Yes it is, they are called Air Rifles. It is a quite interesting topic if you want to do a little research. Believe it or not large caliber air rifles have been used to take a lot of Big Game including dagerous game such as African Lions. Now they were not like what we see a Wally World and buy for the kids, these are true high power large caliber rifles that just used air for a propellent.

http://www.quackenbushairguns.com/

Here is one site that I quickly found offering an example. Now personally I believe that their is a huge amount of improvement necessary before they will be able to become a truly viable alternative to traditional weapons.

Currently the issues revovle around charging them, and getting the pressures high enough to equal or at least aproximate the performace from traditional fire arms. Most of what I see today is similar in performance to the pistol calibur carbines, but were there a high enough demand I think that could be fixed pretty quickly.

 

[Whatsit]

The Soviets had some insight on that topic:

http://world.guns.ru/ammo/sp-e.htm
http://world.guns.ru/sniper/sn20-e.htm

 

[HardKnox]

even with large calibur airguns hearing protection is neccesary, i used to own a 9mm career air rifle, when i used it on the highest velocity setting (somewhere around 900 fps) it was definatly louder than a .22 magnum, i would think that a .50 calibur used for bison hunting would be even louder

i think the only option for quieter bullets is .22cb (even tho an airgun probably has more performance) or sub sonic handloads with a supressor.


oh, and if im not mistaken, the advantages of a supressor are only realized in sub sonic ammo, infact you can achieve pretty close to "hollywood" sound levels.

http://www.youtube.com/watch?v=socgmULGVOA

 

[svtruth]

Your body

will conduct sound nicely, even in space, so you would hear the shot.

 

[SDC]

In line with the above, both the US and Russia have fielded "captured piston" ammunition, which uses a movable piston inside the cartridge case to capture the expanding propellant gasses when that round is fired. The Russian versions are the SP-3, SP-4, and "PZAM" rounds, while the US used (uses?) the QSPR ("Quiet Special Purpose Revolver") and experimented with a scaled-up version in 12 gauge to do the same for shotguns (see below).

 

[PaladinX13]

Yes it is, they are called Air Rifles. It is a quite interesting topic if you want to do a little research. Believe it or not large caliber air rifles have been used to take a lot of Big Game including dangerous game such as African Lions.

This is really misleading in reference to the original post because air rifles of that magnitude are as loud as- if not louder- than traditional firearms. Sound is nothing but moving air and- believe me- large game caliber air guns move a LOT of air (they're a lot less efficient in projectile energy v. sound created than smokeless powder cartridges).

The only reason air rifles are relatively quiet is by virtue of their low power. As soon as you pump that up, it's going to be the same or worse than a firearm. The caveat here is that they can be more effectively suppressed since you're dealing with air and only air- no powder residue, intense heat (although some), etc. But if you can rely upon suppressors then why give up the convenience of the self-contained cartridge?

Bottom-line, don't get yourself a 9mm Career (powerful airgun) expecting it to be as quiet as your Walmart Crosman... sound just doesn't work that way.

 

[HardKnox]

hmm, i wonder if a DIYer would be able to make an piston type cartridge, that sounds like a really good solution, i also wonder what the legalities of owning one would be? probably nothing against it because it is so unknown

 

[Michael Courtney]

Most of the muzzle blast (sound) is produced when the expanding gasses reach the end of the barrel and the pressure wave is then transmitted through the air as sound. To reduce the sound, you need to reduce (or eliminate) the pressure front of the expanding gasses, so you basically need to have something else applying the force to accelerate the bullet.

 

[SDC]

hmm, i wonder if a DIYer would be able to make an piston type cartridge, that sounds like a really good solution, i also wonder what the legalities of owning one would be? probably nothing against it because it is so unknown

I'm certain it's possible (the Russians just use a tapered piston dropped into a necked cartridge case before they put the neck on), but I believe ATF has decided that each round of this ammunition is considered a "silencer" in and of itself, ie. you'd have to register each one and pay a $200 tax on each one.

 

[esmith]

You cant hear anything in a vacuum. Which is what space is. Theres no matter to carry the sound, so you do not hear the sound.

 

[jefnvk]

I do know subsonic rounds out of my CZ452 are pretty quiet, enough that I normally don't wear ear plugs if its the only gun I shoot.

 

[JesseL]

I'm surprised no one has mentioned any cartridges like the 300 Whisper. While it's not quiet enough to be used unsuppressed without hearing protection, it is supposed to be dramatically quieter than you would expect for it's ballistics.

I believe it accomplishes this primarily by using small charges of fast powder to produce a pressure curve that starts very high to get the bullet up to speed, and then falls off quickly by the time the bullet reaches the muzzle.

 

[General Geoff]

re; gas operated semi autos in space:

I have a feeling that most semi autos operated in space would self destruct in short order. Yes, the bolt will cycle, but the problem is the complete lack of opposing air pressure that the atmosphere would normally provide. As such, not only would the bolt cycle, but it would cycle violently and possibly self-destruct due to a lack of equalizing air pressure. I'd imagine a stronger spring would negate this problem, though.

 

[JesseL]

I have a feeling that most semi autos operated in space would self destruct in short order. Yes, the bolt will cycle, but the problem is the complete lack of opposing air pressure that the atmosphere would normally provide. As such, not only would the bolt cycle, but it would cycle violently and possibly self-destruct due to a lack of equalizing air pressure. I'd imagine a stronger spring would negate this problem, though.

You might want to rethink that.

Atmospheric air pressure at sea level is around 14psi. Chamber pressure on a typical gas operated rifle is in excess of 45,000psi. By the time the bullet passes the gas port pressure will have dropped of course, probably to around 10,000 psi. So the difference in relative pressure on the rifle's gas system between operation at sea level and the vacuum of space will be around 0.14%.

 

[PaladinX13]

To reduce the sound, you need to reduce (or eliminate) the pressure front of the expanding gasses, so you basically need to have something else applying the force to accelerate the bullet.

Which isn't to say (and I'm not saying you were implying this, but some might be lead to think it) that railguns are necessarily quiet either.

 

[unspellable]

12 gauge

There is a special purpose 12 gauge shotgun with an extremely long barrel. It is used with subsonic loads, which run a lower pressure than standard loads. The barrel is long enough that by the time the shot exits the muzzle the pressure has dropped to quite a low level and the sound is much reduced. I have forgotten exactly how much.

The barrel is far too long for use in hunting. It is intended for pigeon or crow control in parks and the like. I suspect crows would soon grow wise to it. Pigeons are a bit behind crows in the intellectual pursuits.

 

[heypete]

I have a feeling that most semi autos operated in space would self destruct in short order.

Possibly, but not for the reasons you think -- the vacuum of space, and the extremes of heat or cold (depending on whether one is in sunlight or shade) would cause any lubricants to either boil away or freeze solid, gumming up the works of the gun in short order.

Also, the thermal stresses experienced by an space-cold gun firing a cartridge that generates great pressure and heat might cause the steel to shatter or otherwise malfunction.

 

[Amish_Bill]

I recall being impressed by how quiet a long-ish barreled 32-20 lever gun was.

 

[the naked prophet]

To get "quiet" as in, from 165 to maybe 120 decibels, you can reduce the case capacity (lower the potential volume of expanding gas), increase the volume of the barrel (larger bore size and longer length- the more the gas expands while still in the barrel, the less noise it has to expand once it leaves), change the pressure distribution (faster powder will have higher pressure at the beginning, but drop off quickly, leaving a lower pressure at the muzzle), and use a bullet with lower coefficient of friction (lead bullets instead of jacketed - lower pressure can be used to push the bullets to the same speed).

A heavy-for-caliber, large bore, short case, long-barreled carbine would be ideal. IE a 250 grain lead round nose loaded into a .45 ACP case from a 30 inch barrel should be fairly quiet. That sucker is going to be going awfully slow, maybe 600 fps?

To increase the oomph, maybe load up an 1000 grain solid lead slug into a .500 S&W magnum carbine with a long barrel? Should be fairly quiet, since that would leave little room for powder. The slug would probably have to be tapered at the rear, to allow for the case thickness.

If I had a .500 S&W magnum carbine, with some lead rods and reloading dies for it, I might try that!

 

[TCB in TN]

This is really misleading in reference to the original post because air rifles of that magnitude are as loud as- if not louder- than traditional firearms. Sound is nothing but moving air and- believe me- large game caliber air guns move a LOT of air (they're a lot less efficient in projectile energy v. sound created than smokeless powder cartridges).

The only reason air rifles are relatively quiet is by virtue of their low power. As soon as you pump that up, it's going to be the same or worse than a firearm. The caveat here is that they can be more effectively suppressed since you're dealing with air and only air- no powder residue, intense heat (although some), etc. But if you can rely upon suppressors then why give up the convenience of the self-contained cartridge?

Bottom-line, don't get yourself a 9mm Career (powerful airgun) expecting it to be as quiet as your Walmart Crosman... sound just doesn't work that way.

You are right that they are not as quiet as a smaller cal air rifle but typically much quieter than a traditional gun of similar power. I have never personally shot one but have seen a couple shot and they are definitely quieter.

 

[PaladinX13]

They're not "quieter than a gun of similar power" from my experience. They're usually significantly less powerful for all their bluster. A Career 9mm's putting out only a little over 100 ft-lbs... if I handload a .357 to the same specs, it's about as loud coming out of a revolver and significantly quieter than the air-rifle coming out of a lever-action carbine (about the same barrel length as the Career) which means- to me- that for the same power, air is far more noisy than powder.

We don't even have to get into high-end guns to test this.

If we use CB Caps or Colibri Primer-only rounds and compare them against a Benjamin Sheridan 392 pump gun chronied to produce the same results, you notice the 392 has a sharper crack and arguably louder bang (I don't have a decibel-meter). Although, in that range, the airgun will usually be more accurate as a issue of ammo consistency....