Snipers

[Mister Frag 0]

More importantly, those rifles are equipped with NVDs, so suppressing the flash on what are probably 1st Gen amplifiers was crucial.

[Maraudeur 0]

My two cents.

Hum, first, sory, my english is not that good, I'll try to put my means just like I can, not like I would like to.

Noises from gaz expension in the atmosphere at the barrel muzzle and sonic crach from the supersonic bullet produces two very different noises.

While beeing firedt at by a rifle, location is made by your brain using your knowledge of the sounds laws since you're a baby.

And for your ears and brain, locate in 3D ( or just have an idea, a feeling about if you prefer ) the way ( azimut ) and distance from the source is far more difficult with supersonic crach than from gaz expending in forms like a sphere.

That is one reason why you could use a suppressor with regular supersonic cartridges.

But in fact the gain is low, because of the tactical laws of engagement for snipers. Using this ( supersonic bullets but suppressor )will not provide a real decisive advantage in concealment terms, and sniper will always select firing positions in order to defeat ennemy's researchs. - Ex : firing from very long ranges, like 800m and more do not let from the target point of vue - aspect ? - many possibilities from the sniper's position, in terms of ground relief, etc... I mean the necessity to have a line of fire with an operationnal possibility of presence ( ingress and egress ways, more....).

Another way to determine sniper's position, did automatically by humans, is when realising where the victim have been hurt ( if visible ), how he fels, were he was before beeing fired at, the impact sound ( yes ), etc....

And always necessity to move fast after firing.

So use of suppressor just can give some ->little<- more time to evade before seeing a blind spray of fire from the other side guys ( as locating the supposed way from the threat is more difficult ), to try a lucky shoot, or prevent second or more incoming deadly shoots from ambushed sniper. So it may be gives a little more tactical flexibility when choosing where an when to fire or not, but tha difference is not great, counting on it could be very dangerous by passing away the " classicals " methods and limits. Play with fire.

In fact, snipers will respect tactical rules about where, when and how to shoot or NOT and use hunting spirit to prevent disagrements like return of fire or sniper's hunting

One of the availables techniques, to stay in the subject with sound concealment is for example, to stay aprox. 2 meters behind a stone ( if available or any other big solid object ) and just let the way for the bullet to go at the side of that stone. So both the sonic boom and gaz expansion sounds will know distorsions that will made localisation harders, or product false echos. ( and maybe more if in conjonction with others elements, fire in a valley, near a hill, houses, forest corner in front of the shooter and near of him on the other side of the stone, etc...)

That's for ambushes or elimination selective fires.

For use in conjunction with first line front troops, the advantage is equal to zero because concealment is near to zero, and engagements are not in the same maner at all. More a supporting unit for rapid and decisive response, or first selective fire. Missions where concealment is not totaly necessary and not really reachable.

P.S : Yes, suppressors do not affect accuracy, and yes, even at 600 meters from the target for example ( and depending to light exposure of the sniper's position ) things like foliage moves after fire are enough to capt attention of some humans ( brain and human sensors like eyes and ears could reveal abilitys that many would be surprised to discover for themselves ) enough to have a guy saying : " Hey, -- I feel/ I'm sure -- it's coming from there ! " pointing an index at an approximative direction.

And you'll see all the incredible volume of fire modern automatic's squad weapons could give fell around you, from light machineguns, assault rifles, grenade launchers and rockets launchers. Not really aimed at you, but it's not necessary to be very dangerously unpleasant ! lol !

P.P.S : Yes, holes in a barrel to reduce under sonic level bullet velocity exists, since long time : HK MP5 SD. Hk advertise best results are with full power cartridges

P.P.P.S : Muzzle flash, by day, with correct ammo, not to high temperatures and low day lights, with barrels now long commonly 65 centimeters with heavy bullets flash hiders lacks is not a real handicap. But.... with flash hiders it's better !

- On the other way, if they are well designed, they can be very efficient for reducing foliage moves, and  more...dust. But really flash hidders and suppressors do not affect bullet stability by gaz moves, or in proportions so thin that even match and  bench rest shooters can't see the difference. But barrel cut and bushing does affect bullet stability ( vacuum effect ? lol ), also the manner the rifling ends. ( and more a problem with conventionnal rifling than polygonal - since years, polygonal is as accurate than standard rifling, by button rifling and not hammering )

[bn880 5]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Maraudeur @ July 12 2002,16:05)</td></tr><tr><td id="QUOTE">But barrel cut and bushing does affect bullet stability ( vacuum effect ? lol ), also the manner the rifling ends.<span id='postcolor'>

WOW Impressive!

Well, actually vacuum is just a difference in pressures...

Even the barrel cut affects the vacuum (so called turbulance) the round experiences when leaving the muzzle.

What I was thinking about is that in the length of the sound supressor, if the round is traveling at 3000fps and the gas is slowed to 500fps then the round will have a small vacuum behind it.

Difference in pressures.... this is just a deduction.

May sound nice and simple to say barrel cut and bushing but it has alot to do with gas pressures (dynamics).

[Guest]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (bn880 @ July 12 2002,22:33)</td></tr><tr><td id="QUOTE">Well, actually vacuum is just a difference in pressures...

Even the barrel cut affects the vacuum (so called turbulance) the round experiences when leaving the muzzle.<span id='postcolor'>

Lol. Not really. Vacuum is not difference in pressure. Vacuum is a region which is virtually void of gasses. The pressure in vacuum is called absoulte zero and is a reference for all other pressures.

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">What I was thinking about is that in the length of the sound supressor, if the round is traveling at 3000fps and the gas is slowed to 500fps then the round will have a small vacuum behind it.

Difference in pressures....  this is just a deduction.<span id='postcolor'>

It is amazing how many times I have to repeat this: The muzzle velocity of the bullet is affected by the pressure in the barrel and not the pressure outside the barrel. Also for the fifth time, the gases come out *after* the bullet. So suppressor or no suppressor, it makes no difference (assuming that the muzzle crown is ok on the weapon, but that's another story).

Maraudeur's post was entirely correct.

[bn880 5]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (denoir @ July 12 2002,16:45)</td></tr><tr><td id="QUOTE">Lol. Not really. Vacuum is not difference in pressure. Vacuum is a region which is virtually void of gasses. The pressure in vacuum is called absoulte zero and is a reference for all other pressures.

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">What I was thinking about is that in the length of the sound supressor, if the round is traveling at 3000fps and the gas is slowed to 500fps then the round will have a small vacuum behind it.

Difference in pressures.... this is just a deduction.<span id='postcolor'>

It is amazing how many times I have to repeat this: The muzzle velocity of the bullet is affected by the pressure in the barrel and not the pressure outside the barrel. Also for the fifth time, the gases come out *after* the bullet. So suppressor or no suppressor, it makes no difference (assuming that the muzzle crown is ok on the weapon, but that's another story).

Maraudeur's post was entirely correct.<span id='postcolor'>

Well you are defining vacuum more precisely that's all, I'm trying to keep this short. (Vacuum, look in a book I don't care)

EDIT: Reading that again you are defining Vacuum as in Vacuum in space, I am talking about Vacuum as in suction, or as in manifold vacuum in an engine.

As to your last paragraph:

Obviously you do not actually understand gas dynamics if you are repeating that and think that a round leaving the muzzle first is not affected by slower gases behind it (while in barrel or supressor). There could be a small effect, depends on the design of the supressor (so maybe not).

I'm just trying to discuss it. It seems to me like you are not at all open minded. This is not a disagreement, nothing to prove, nothing to gain here!

[Warin 0]

I am amazed at the people that continue to disagree with Denoir when pretty much everyone who actually knows has chimed in with 'he's right'

Despite what crackpot ballistic theories you may or may not have...Denoir has pretty much explained things how they are.

Can we move on now?

[bn880 5]

I didn't realize this topic was about proving someone right, or wrong.

Done posting in it for sure.

What's the point.

[Warin 0]

It's not proving someone right and wrong..it's people asking the same question over and over and ignoring the answer given already.

And it wasnt aimed at anyone in particular.

[Guest]

0--></span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (bn880 @ July 12 2002,230)</td></tr><tr><td id="QUOTE">Obviously you do not actually understand gas dynamics if you are repeating that and think that a round leaving the muzzle first is not affected by slower gases behind it (while in barrel or supressor).  There could be a small effect, depends on the design of the supressor (so maybe not).  

<span id='postcolor'>

Fine have it your way. I genuinly despise thermodynamics, but I have had the unfourtune that thermodynamics is part of every standard engineering curriculum, including Electrical Engineering. I'll explain briefly the physics behind my arguments in layman's terms.

There are four pressures involved in the problem:

P1 = pressure in the muzzle behind the bullet

P2 = pressure in the muzzle in front of the bullet

P3 = pressure in the suppressor

P4 = pressure in the outside world

At the moment the bullet is fired P2 = P3 = P4 according to the Boltzmann gas law (the pressure is equalized since the contact surface between the pressure areas are open).

The bullet can be seen as a piston traveling down the barrel.

The force applied to the bullet is the average sum of the forces from the gas molecules that are colliding with the bullet. The molecules in pressure area 1 apply a much bigger force then the one from the other areas because of the great kinetic energy they got by the ignition of the bullets propellant.

If we take a infinitely small element of distance that the bullet travels (dx) and also an differential element of time (dt)and see how the force changes we get:

(1) F*dt = dP = 2m*v(dx)    (Newton's law)

(2) P = 2*N/3*V * average (1/2 m*v^2) (Kinetic Gas Law)

(3) P*V = N*k*T (Ideal Gas Law)

N is the number of molecules, k = Boltzmann's constant, T = temperature.

The pressure P1 = P1(t, T). We cannot state it in a trivial way since it depends on time and temperature, but it is irrelevant, as I will show.

The force that act on the bullet is F1...F4. Since the surfaces between pressure areas 2,3,4 are still open then average(F2)=average(F3)=average(F4). Moving the piston (bullet) a distance of dx in the time dt gives a velocity of v = dx/dt. (3) guarantees us a constant Pressure * Volume if the temperature is the same. That is not valid behind the bullet, but it is in front of it. At the end of the muzzle, in the beginning of the suppressor the pressure drops as the volume increases. This causes according to (1) F1 do decrease. However F2=F3=F4 stays the same according to (2). What does this mean then?

1) The force that pushes the bullet decreases. Note that decreases doesn't mean that it is reversed. It has the same direction, but smaller. (Much smaller, about 500 times smaller since a suppressor has about 500x the volume of the barrel).

2) The forces acting in front of the bullet are the same, zero in average (F2=F3=F4 still holds).

SO, to conclude, with the suppressor the bullet gets a force about 500 times smaller then the one in the barrel. That force would have not existed without the barrel. So in theory a suppressor will actually increase the speed of the bullet. This increase is however so small that it is negligible.

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">I'm just trying to discuss it. It seems to me like you are not at all open minded. This is not a disagreement, nothing to prove, nothing to gain here!

<span id='postcolor'>

While, I'm all for discussions, this is physics. There are a set of natural laws that cannot be changed no matter how much we discuss them

[Placebo 28]

Ya canna change the laws of physics Jim

[mithrandir 0]

This site has allot of information about longrange sniping, equipment and tactics!

http://home.swipnet.se/longrange/

[Tex -USMC- 0]

Good God, Im surrounded by friggin geniuses... This forum is one of a kind

[Tovarish 0]

Hey guys, check this out, a Canadian sniper in Afghanistan just broke the record for the longest-range kill.

Long Shot Pays off

[Jester983 0]

Damn Denoir... While you're at it would you like to tell us the meaning of life?

[bn880 5]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">There are four pressures involved in the problem:

P1 = pressure in the muzzle behind the bullet<span id='postcolor'>

What I was concerned about, or in your case P1 which goes to P3.

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">1) The force that pushes the bullet decreases. Note that decreases doesn't mean that it is reversed. It has the same direction, but smaller. (Much smaller, about 500 times smaller since a suppressor has about 500x the volume of the barrel).<span id='postcolor'>

Now there, I was considering if the pressure of the gas in P3 is so low that it does not expand sufficiently fast to provide more muzzle 'push' (or acceleration) for the round (since the round has been accelerated by greater pressure P1), or even if the expansion is slower than the speed of the round, which would create a vacuum (suction) right behind it in P3. However, I figure that the gas is not slowed down that much (pressure is greater than required).

In which case your statement about providing a higher velocity is proven.

[DarkLight 0]

First of all, thanks for answering on my questions Denoir, very usefull information. Same for Maraudeur, very nice things too.

Denoir => I tried reading your last post, i made it until the drawing, pretty damn impressive but a little too hard for me I sure hope i'll never have to learn that kinda stuff.

Do you know all that or did you just copy - paste it from some website that you've found ?

[bn880 5]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (denoir @ July 12 2002,18:04)</td></tr><tr><td id="QUOTE">While, I'm all for discussions, this is physics. There are a set of natural laws that cannot be changed no matter how much we discuss them <span id='postcolor'>

Well sure, but all the laws of Physics do not eliminate the need for experiments and analysis.

And don't forget that our Physics laws are still missing some addons.

[DarkLight 0]

Oh btw, feel free to post as much as you like about anything related to sniping here. I love it and i think it's a very interesting subject. I don't know much about it so all information is welcome

[Guest]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (bn880 @ July 13 2002,00:28)</td></tr><tr><td id="QUOTE">Now there, I was considering if the pressure of the gas in P3 is so low that it does not expand sufficiently fast to provide more muzzle 'push' (or acceleration) for the round (since the round has been accelerated by greater pressure P1), or even if the expansion is slower than the speed of the round, which would create a vacuum (suction) right behind it in P3.  However, I figure that the gas is not slowed down that much (pressure is greater than required).

In which case your statement about providing a higher velocity is proven.   <span id='postcolor'>

The only way that 'suction' would occur is if the pressure behind the bullet would be lower then the pressure in front of it. And that can never happen, regardless of suppressor

The gas in P3 has the same pressure as P4 in front of the bullet so again, it doesn't matter if you have a suppressor or not.

What is essential here is that the force applied is the sum of the forces from the colliding particles. If the pressure drops it means that the particles collide less often. That doesn't mean that a force in the opposite direction is created, not at all. If you have two pressures P1 < P2 then particles from P2 will travel to P1. The pressure behind the bullet is always greater then the pressure in front of it during its acceleration, so there is no 'suction', there is no opposing force

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Well sure, but all the laws of Physics do not eliminate the need for experiments and analysis.

And don't forget that our Physics laws are still missing some addons. <span id='postcolor'>

I agree, but these are things that we have tested and confirmed for over 200 years now, so I think we can count on them as reliable

[bn880 5]

That's for a 'piston' that is stationary. The round (our piston) has alot of speed, and even though the gas in P1 or P3 may be of higher pressure than P4 (outside) the speed of the round may still create a vacuum.

(even though u got higher pressure, maybe the fluid/gas [air] will not expand fast enough to accelerate the piston)

Ok, that's if the pressure dropped lower than what we are considering.

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">I agree, but these are things that we have tested and confirmed for over 200 years now, so I think we can count on them as reliable<span id='postcolor'>

Yea I know, I'm just saying in general. It's meant to be funny.

[Guest]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (DarkLight @ July 13 2002,00:32)</td></tr><tr><td id="QUOTE">Denoir => I tried reading your last post, i made it until the drawing, pretty damn impressive but a little too hard for me I sure hope i'll never have to learn that kinda stuff.

Do you know all that or did you just copy - paste it from some website that you've found ?<span id='postcolor'>

Unfortunately not I missed 15 minutes of the start of a rerun of Sopranos that I wanted to see. I must say though that I really, really, really hate thermodynamics. I only know it because I was forced to learn it.

Thermodynamics is a heap of bullshit with the only benifit that it adds up experimentally. Don't get me started on how much I hate it and what utter crap the so called 'theory' is.

[DarkLight 0]

Question, i'm sorry if this has already been said but i'd like to know it.

You guys say that a bullet flying through the air and that the impact of the bullet makes noise, right? (i wasn't sure about the flying through the air "noise" so correct me if i'm wrong please)

But can these elements actually show the location of a sniper?

Other question, when a gun (with a silencer) is fired, the gun will make a "popping" noise, right? Of course you can still hear some noise, at what range is that "pop" hearable? I repeat, WITH a silencer.

[bn880 5]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (denoir @ July 12 2002,18:48)</td></tr><tr><td id="QUOTE">Thermodynamics is a heap of bullshit with the only benifit that it adds up experimentally. Don't get me started on how much I hate it and what utter crap the so called 'theory' is. <span id='postcolor'>

They called it thermodynamics over there, well maybe they stuck this topic in that course.

Such courses are normally called fluid dynamics.

[Guest]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (bn880 @ July 13 2002,00:47)</td></tr><tr><td id="QUOTE">That's for a 'piston' that is stationary.  The round (our piston) has alot of speed, and even though the gas in P1 or P3 may be of higher pressure than P4 (outside) the speed of the round may still create a vacuum.<span id='postcolor'>

Nope, I did it with dynamics, as you can see from my equations I took into consideration dx/dt = speed of the piston. The bullet accelerates until the pressure on both sides are equalised, which is when it exists the suppressor (or muzzle for all practical considerations).

There is no such thing as 'vacuum' or 'suction'  induced by reduction of speed. As a matter of fact there is nothing called 'vacuum' or 'suction' in physics. The only possibility of an induced force in the opposite direction of the bullets path is if the pressure behind the bullet is lower then in front of it.

[Guest]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (bn880 @ July 13 2002,00:51)</td></tr><tr><td id="QUOTE"></span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (denoir @ July 12 2002,18:48)</td></tr><tr><td id="QUOTE">Thermodynamics is a heap of bullshit with the only benifit that it adds up experimentally. Don't get me started on how much I hate it and what utter crap the so called 'theory' is.  <span id='postcolor'>

They called it thermodynamics over there, well maybe they stuck this topic in that course.

Such courses are normally called fluid dynamics.<span id='postcolor'>

Fluid dynamics is a subfield of thermodynamics