posted
Interesting article. Glassman, didn't you say you have some experience with subsonics? What do you think of their potential solution?
Silent but deadly: Special forces seek quiet, subsonic bullets By Robert Beckhusen, Wired updated 12:07 PM EST, Tue November 20, 2012
(Wired) -- Most bullets make small sonic booms when flying through the air, which to our ears sound like a loud, distinct "crack!" For the Pentagon's special forces, that makes it hard to be sneaky about what they're shooting. Now the commandos want to be sneakier with slower, quieter bullets. In its latest round of small-business solicitations, the Pentagon's Special Operations Command, or SOCOM, is seeking out subsonic ammunition. The reason, according to the solicitation, is to "provide superior covert and stealth capabilities" for not only the military, but police forces and the Department of Homeland Security. In theory, and for rifles in the 5.56, 7.62 and .338 calibers, the bullets will travel at low enough velocities to avoid breaking the sound barrier, thus creating no "crack" noise. Breaking the sound barrier also pretty much negates the use of a sound suppressor, or "silencer," which the special forces would likely want to use against militants in Afghanistan and around the world. At present, the Defense Department does not have subsonic bullets "classified for use in the calibers provided by any DoD service." That doesn't mean special operations forces never use them. Commandos have used subsonic bullets since World War II, though these are mainly effective in smaller guns like the .22 and 9 mm caliber pistols. Subsonic bullets and fairly large-caliber war rifles, on the other hand, don't mix very well. For one, to keep a bullet from breaking the sound barrier -- 1,100 feet per second at sea level -- requires several trade-offs at higher calibers. According to the solicitation, subsonic bullets "experience significant accuracy problems due to excessive deviations in velocity." The gunpowder (or propellant charge) for a subsonic bullet has to be used in smaller quantities than for a normal bullet, and the bullet itself has to be heavier. This results in bullet that is far and away less accurate, doesn't go nearly as far, and "creates lower pressures which ... makes it hard to get a clean burn of the propellant causing rapid fouling of the weapon." In technical jargon, the failure of a clean "burn" and the resulting lowered accuracy and range is called a failure of "obturation." Normally, a bullet expands -- or obturates -- to the size of its barrel after being fired, keeping the bullet on target and preventing the gases that propel it from rushing past and melting to the inside of the gun. The melted leading can be a pain in the ass to remove, and can permanently damage the weapon unless it's cleaned. Likewise, a bullet can't be too light or too heavy, because too much in either direction can prevent the bullet from obturating. Using subsonic bullets also causes a greater risk of jamming, which in a firefight could mean the difference between life and death. Instead, the Pentagon has one idea about how to build a better subsonic bullet. One solution could be using "polymer cased ammunition" as opposed to brass or steel. The Pentagon is somewhat vague about how this will work, but the idea is that polymer-cased bullets "produce a reliable and consistent powder burn." More specifically, polymer obturates at lower pressures, which means it may be possible to shoot a heavy bullet with less propellant while theoretically not trading for accuracy and range. Maybe. To do it, the Defense Department might want to go back to the future. During the late 1980s and early 1990s, the Army spent $300 million on a canceled project called Advanced Combat Rifle to replace the standard M16 rifle. One proposed replacement, the Steyr ACR, used polymer cartridges, but supposedly suffered from inaccuracy due to the strength of the cartridges being inconsistent, though this could be conceivably solved by testing cartridges until they fire consistently. Perhaps SOCOM could do it better.
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posted
yes i shoot almost exclusively sub-sonic .22 ammo.
all the best .22 target ammo is loaded to subsonic speeds. that is because the shck wave associated with breaking the sound barrier does disrupt the flight path of the bullet- it is usually only a matter of a degree which does not mean much when shooting at large targets.... the key to accuracy is repetitiveness of placement of the slugs. I look for a gun to be able to put three bullets within a 1 inch group at 100 yds for high power rifles and 50 yds for a .22 rifle while being clamped in a vice. If they are within a half inch group all the better. I have gotten rid off all my .22 LR's that shoot bigger than 1/2 inch at 50 yds... i often expected to buy three to find one, until i found a couple of small custom makers. after that, there is a ballistics table showing how to addjust your scope for differing conditions.
)that one (.308) is considered a standard all-purpose round... note the amouont of drop... that's strcily a function of how long the bullet is in the air... gravity is constant and pulls the same all th etime...
sub-sonics give away alot of power- that means i have to clean my guns all the time so they can auto-reload or they will jam. I won't say it's impossible to build a combat round that is sub-sonic, but you just plain give up foot-pounds which translates into stopping power and you give up your flat-line trajectory by having to be in the air longer...
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posted
The problems you specify at the end of your post are what they are trying to address. What do you think of their possible polymer solution to those issues?
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posted
the key to silent guns will most likely be electronic coil guns shooting neodymium mgnets. it's doable now, but we do not have batteries capable to provide what we need yet.
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quote:Originally posted by Pagan: The problems you specify at the end of your post are what they are trying to address. What do you think of their possible polymer solution to those issues?
i don't know what they mean by polymer rounds-
polymer projectiles? you still don't have teh foot-pounds to translate to your target....
if this were simply room entry? they already have that. if they are talking about sniping? i don't see a way to do it with gunpowder
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I think they were referring to polymer encased rounds which would allow for the heavier rounds, prevent the fouling issue, and keep the accuracy, range, and inertial power. At least that's the way I read it.
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i could see a large caliber plastc round with a low start load in the shell- then when it has traveled 100 yds? a small rocket engine int heshell could tak over and give you the power and range.... but that is just getting to o complicated and risky for spec ops to put hteir lives on all the time...
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quote:Originally posted by Pagan: I think they were referring to polymer encased rounds which would allow for the heavier rounds, prevent the fouling issue, and keep the accuracy, range, and inertial power. At least that's the way I read it.
polymer shell casings won't change the actual foot pound problem tho.
it's just like a punch- if you take 45 ACP hit on ht eshoulder at ten feet? that is just like getting hit by a 7mm mag (about a 280 cal) at 500 yds.. either way you get spun around and you wont use that arm agin probaly ever..
a .22 at ten feet will get your attention but you won't go doan and you may very well be anble to retune fire immediately cuz you don't even know you got hit for a second or two. it depends on the meat that gets damaged. that's th real probelm here. you take the Velocity off, and you give up foot pounds exponentially. Force equals mass times acceleration--- acceleration is a squared function
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quote:Originally posted by Pagan: I think they were referring to polymer encased rounds which would allow for the heavier rounds, prevent the fouling issue, and keep the accuracy, range, and inertial power. At least that's the way I read it.
polymer shell casings won't change the actual foot pound problem tho.
it's just like a punch- if you take 45 ACP hit on ht eshoulder at ten feet? that is just like getting hit by a 7mm mag (about a 280 cal) at 500 yds.. either way you get spun around and you wont use that arm agin probaly ever..
a .22 at ten feet will get your attention but you won't go doan and you may very well be anble to retune fire immediately cuz you don't even know you got hit for a second or two. it depends on the meat that gets damaged. that's th real probelm here. you take the Velocity off, and you give up foot pounds exponentially. Force equals mass times acceleration--- acceleration is a squared function
Hence the HEAVIER round, to keep the same stopping force. At least that seems to be what they are stating in the article.
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heavier rounds? not as good as velocity. basic physics: acceleration is CHANGE in Velocity it's squared function while mass is a linear function... this problem is old.
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there is another solution, and that would be impreganting the action parts of the gun with nan-tech- "lubricating" in the same manner that we produce doped semiconductors... peopel like to throw around th term nano-tech with abandon, they could call it nano tech, but it would be advanced matellurgy... parts would cost a fortune but that is good for biz...
alternative to lubricating, the doping materials could just promote 'self" cleanng by repulsive action... like that stuff you use on your windsheild to make water bead up?
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The Steyr ACR is the most notable user of polymer cased ammunition. It is a bullpup, rimfire rifle, that shoots a 5.56 X 45 mm flechette cartridge. The muzzle velocity is 4,757 ft/s. The flechette design allows it to retain much of its velocity and kinetic energy as it travels through the air; making it shoot very flat. This allows the rifle to be "sighted in" at 50 yards and still maintain close to the same point of impact out to a range of 300 yards or farther. The Steyr IWS 2000 is a closely related anti-material rifle. It shoots a 15.2mm saboted, fin-stabilized, armour-piercing flechette made of tungsten carbide or depleted uranium.
flecchette is wierd stuff.. it's more or less illegal- if we are going here? the may as well go all the way tho...
the sabot solution causes inaccurracy because of the air disturbance you create as the sabot casing drops away... it can be minmized, but you are stilltalking about very specialised quality conrtol problems in production...
my limited experince with flechette is in shotguns. and it can go thru a tree and take out the guy hidin on hte back side... i heard tales for the 'nam wher it was used on the trails to take out four and five combatants in line... dunno if it's true, but i got it from a gunner. the m-60 gunners like a 12 guage for backup cuz the m-60 jams if you even look at it wrong.
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I would think most use suppressors if they need quite, or knives if sleeping.
Maybe not as good as what there talking about, i guess.
Good for jobs to always make something better or something new someone might want. Like i phones, don't bring out your best version first, keep adding as you go.
posted
another solution to a self cleaning gun? put a piezo-electic crytal in each round- piezo's are how the "snap" lighters emit a psark... then put a matching charge onthe gun so the charged powder is repulsed.. could work, i don't have time to research the piezo charge in-depth to make definitive suggestion long literature search but it could work too...
flechet guns without sabots are another machining problem that we could solve too...
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Well, the point of the article was the DoD is looking to make the perfect subsonic round. They want to retain the accuracy, range, and stopping power. So I imagine there should be many companies scrambling to meet the criteria. Will be very interesting to see what they come up with. That is if that info will even be released, doubtful it will be made public if they solve the aforementioned issues that we are discussing.
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i have always tried to avoid the miltiary stuff pagan.. they don't really want you to set tehm up with your ideas, they want you to hire one of them to cinsult for five years and then they coem up with your idea on their own... seen it happen..
when i was in? i made several suggestions that the navy get into kite flying...
sounds dumb right? not. we could fly aluminum kites off of destroyers and even smaller boats that would make them appear to be aircraft carriers on radar... we could even appear to be a a whole fleet of aircraft carriers on radr... and cheap too... way cheaper than BPDMS and other coutnermeasures... to my knowledge? they never pursued it. chaff charges last for a few minutes, a kite will last till it gets hit, and hten you realease another... (ballons would also work too)
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quote:Originally posted by glassman: i could see a large caliber plastc round with a low start load in the shell- then when it has traveled 100 yds? a small rocket engine int heshell could tak over and give you the power and range.... but that is just getting to o complicated and risky for spec ops to put hteir lives on all the time...
They already have those glass. They can also use laser designating tech in conjunction with them.
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the Steyr ACR at above 4500 FPS is about as fast as any chamebered round and will most definitely give the sound barrier "crack"... so i'm not sure where the article is actually coming from.... i shoot a 25-06 that is about hat speed and the 22-250 is just abit faster... they are so loud you can go deef without protection
milspec certification is a nightmare....
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quote:Originally posted by glassman: the Steyr ACR at above 4500 FPS is about as fast as any chamebered round and will most definitely give the sound barrier "crack"... so i'm not sure where the article is actually coming from.... i shoot a 25-06 that is about hat speed and the 22-250 is just abit faster... they are so loud you can go deef without protection
milspec certification is a nightmare....
Which post are you responding to? You lost me on that post.
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quote:Originally posted by glassman: the Steyr ACR at above 4500 FPS is about as fast as any chamebered round and will most definitely give the sound barrier "crack"... so i'm not sure where the article is actually coming from.... i shoot a 25-06 that is about hat speed and the 22-250 is just abit faster... they are so loud you can go deef without protection
milspec certification is a nightmare....
Which post are you responding to? You lost me on that post.
that is the weapon mentioned in the original article....
you know waht? if you aren't squeamish? and you don't care about the Genva convetion anymore? the paintball gun using hydrogen cyanide or nicotine sulfate instead of paint is the best silent weapon you could want, low tch cehap and easy... they could easily beef the system up to 200 yards and have interchangeable barrels to go from the paintball type ammo to darts and maybe even double that with a protbale system...
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the article is not really clear on what the govt wants.
for instance? we already have .410 (that's .41 inches) shotgun semi-auto based on the kaleshnikov that runs polymer shells and polymer wadding to gain a high level of obduration...
a decent solution could be based on that system even down 30 calibre IMO... the problem is that no matter how you slice it, subsonics are slow and have limited range. and power
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BTW Pagan thanx for posting this... i have done some more searching now and i see the problem they want to solve, they are willing to give up range for consistency i do have a couple ideas that might help...
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wehn rifles were first invented? they used a patch (just a peice of cloth) to seal the ball to the rifle bore (obduration)...
so the solution to this is going to be a new patch and a very fast, but small clean burning HE load of powder.... an oxidizing agent will get rid of the residue, but you can't use too much or you'll damage teh gun metal.....
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