Design an air rifle for the military

[airgun_novice]

Yes were were also briefed on the same lines in NCC when I had asked the rationale for switching from 7.62 to 5.56.
I was told something on the lines of "Dushman ko causalty karna hai, marna nahi hai"

Sometime back someone told me of this "5% Rule" in combat. It seems only 5% of the regular fighting force end up killing most of the other side while 95% simply end up (deliberately or sub-consciously) shooting the backdrop or the ground or at the best injuring but not terminating the enemy. Unless the shooters come from a "highly motivated" team like the Seals or snipers, then the percentage gets significantly higher.

Found it fascinating at the time - still do. Why ? Here are soldiers who are supposed to kill with a gun and yet in the deepest crevices of their heart are not killers, but we have some civilians who have no qualms killing a newly born baby simply because it's a girl or a daughter-in-law for few pieces of silver.

[timmy]

This seems to me to be a reasonable subject for discussion and exploration -- at least, it cannot be a fruitful exercise to dismiss ideas that, perhaps, violate intuition. I believe Galileo violated intuition, along with the Church's dogma, and came up with some pretty interesting findings that are still of use today.

Anyway, I think it might be best if the project started with identifying a use. This will give an idea of the range and power needed to do a specific job. After this, the power necessary can be determined, and a suitable source of air (portable or not) sought to fill the bill.

[bennedose]

Anyway, I think it might be best if the project started with identifying a use. This will give an idea of the range and power needed to do a specific job. After this, the power necessary can be determined, and a suitable source of air (portable or not) sought to fill the bill.

This is what I thought.

I was wondering if it would be possible to develop useful sniper rifle, silent and powerful. I have some calculations coming up, but I will leave that out for now - I am no physicist and have to struggle somewhat to do that.

As far as my guess goes I thought perhaps a 130 to 180 grain (10 - 15 grams) pellet/bullet must be made to fly accurately for at least 500 meters and retain enough power at the end to be useful. I will attempt to post some figures on this issue later. I suspect that this is asking a lot of an air powered rifle, considering that real life snipers have hit targets at 1000 or 2000 meters. But I just assumed that this would be a start. There are videos on YouTube of police snipers getting targets at closer range to disarm or disable a hostage taker. I guess even 200 meters would be a useful range in the close confines of an urban environment.

[essdee1972]

Bennedose, why don't you look at a shorter range air weapon for urban hostage situations? The Mumbai police, reportedly, have purchased a 0.50 cal sniper rifle which is sheer overkill (pun not intended, but very apt!!) for urban situations. A powerful enough air weapon might work better. Or would a crossbow serve the purpose? (just thinking!)

Probably you can start with tranquiliser guns as the base? To penetrate an elephant's hide would take a lot of power, I assume?

[timmy]

Hmm. I am seeing 10 grams as 154 grains. I'm thinking of the old .30-30, long considered a good deer rifle. It is said that, for hunting purposes, the cutoff is around 1000 ft-lbs (about 1355 joules) of energy, and for a .30-30, that is about 200 yards. At that point, the 30-30 bullet, sighted in for 100 yards, will drop about 8 inches at 200 yeards. The .30-30 starts off with about 2000 ft-lbs of energy to push a 150 grain bullet fast enough for this kind of performance.

It is recognized that a .30-30 bullet is no great shakes at ballistic performance, because of the tubular magazine requirement. But we could talk about bullets later -- it sounds to me as if we need, maybe, 2500 joules of energy?

Bullding on essdee's thought, there is that cartridge called the .458 Barnes that was developed to be silenced (bullets slower than the sound barrier ~ 1000f/s) and bash through the jungle. It was made up on 1.5" 458 Winchester cases. That 20 gram bullet will launch at 1800 f/s and requires about the same kind of energy.

Comparing these levels of energy with today's airguns indicates that the mechanism of the big bore airgun is going to be different!

Black powder works better for larger bores, say, 9.5 mm and up. I wonder how air would work -- would there be a caliber that works best? Perhaps this would depend on whether one was using compressed air, or a springer-type mechanism, or whatever is identified as a workable solution.

It might be fun to play around with such a thing!

[bennedose]

Essdee a tranquilizer gun model is an interesting idea - but the skin penetration is achieved by a very fine point. This actually expands the focus from mere design of high power rifle to a parallel design of projectile that does the intended job despite lower rifle power.

The thought that strikes me is what I have heard from military circles (and discussions in hunting circles) about smaller calibers, higher velocity, hollow points, soft nosed/snub nose and tumbling bullets. Too fine a point or too small a pellet will simply pass through the intended target leaving a drill hole and less damage. A larger projectile stops within a target and expends all its energy doing damage to the target.

But what impressed me about some hostage scenarios is the way the police sharpshooter gets the hostage taker's exposed body part while a hostage is being used as human shield.

[timmy]

This is true about just a sharp, or spitzer type of bullet. But the British found out long ago with the .303 that making the bullet inherently unstable caused it to tumble on impact, so that it "keyholes" the target and expends its energy causing damage internally, instead of punching nice, neat round holes. The latest 5.56x45 military ammo was designed to work this way, after the Soviets revived the principle of unstable .303 bullets for their 5.45x39 round.

I would presume that, if a special use weapon did not use expanding projectiles, for whatever reason, it would use this same principle of instability in order to maximize its effectiveness.

[TwoRivers]

Probably you can start with tranquiliser guns as the base? To penetrate an elephant's hide would take a lot of power, I assume?

With what is essentially a big barbed hypodermic needle ?

[TwoRivers]

The thought that strikes me is what I have heard from military circles (and discussions in hunting circles) about smaller calibers, higher velocity, hollow points, soft nosed/snub nose and tumbling bullets. Too fine a point or too small a pellet will simply pass through the intended target leaving a drill hole and less damage. A larger projectile stops within a target and expends all its energy doing damage to the target.

No. Whether a bullet penetrates the target or stays inside the target is not a function of bullet size (diameter), but of bullet construction, its sectional density, and velocity. Wouldn't a bullet that makes it through the target have expended more energy in doing so than one of similar construction that didn't make it all the way through ?

[bennedose]

Hmm. I am seeing 10 grams as 154 grains. I'm thinking of the old .30-30, long considered a good deer rifle. It is said that, for hunting purposes, the cutoff is around 1000 ft-lbs (about 1355 joules) of energy, and for a .30-30, that is about 200 yards. At that point, the 30-30 bullet, sighted in for 100 yards, will drop about 8 inches at 200 yeards. The .30-30 starts off with about 2000 ft-lbs of energy to push a 150 grain bullet fast enough for this kind of performance.

It is recognized that a .30-30 bullet is no great shakes at ballistic performance, because of the tubular magazine requirement. But we could talk about bullets later -- it sounds to me as if we need, maybe, 2500 joules of energy?

Bullding on essdee's thought, there is that cartridge called the .458 Barnes that was developed to be silenced (bullets slower than the sound barrier ~ 1000f/s) and bash through the jungle. It was made up on 1.5" 458 Winchester cases. That 20 gram bullet will launch at 1800 f/s and requires about the same kind of energy.

Comparing these levels of energy with today's airguns indicates that the mechanism of the big bore airgun is going to be different!

Black powder works better for larger bores, say, 9.5 mm and up. I wonder how air would work -- would there be a caliber that works best? Perhaps this would depend on whether one was using compressed air, or a springer-type mechanism, or whatever is identified as a workable solution.

It might be fun to play around with such a thing!

OK this is some seriously useful info. So let me mull on this and see if I can conjure up barrel lengths to generate such energies from a 3000 psi source.

[bennedose]

No. Whether a bullet penetrates the target or stays inside the target is not a function of bullet size (diameter), but of bullet construction, its sectional density, and velocity. Wouldn't a bullet that makes it through the target have expended more energy in doing so than one of similar construction that didn't make it all the way through ?

No a bullet that flies through a target retains some energy to keep on flying and that energy will be expended as it flies through the air and slows down, or by hitting something else in the back - say a wall or something to make a dent. A bullet that stops inside a target loses all its energy inside the target.

Having said that it is theoretically possible that a very high energy bullet from an assault rifle could still leave behind more tissue-damaging energy in a target (by cavitation) than a handgun bullet that stops in a target. But an assault rifle bullet that stops will expend all its energy in a target unlike a corresponding assault rifle bullet that penetrates.

[TwoRivers]

[quote="
Having said that it is theoretically possible that a very high energy bullet from an assault rifle could still leave behind more tissue-damaging energy in a target (by cavitation) than a handgun bullet that stops in a target. But an assault rifle bullet that stops will expend all its energy in a target unlike a corresponding assault rifle bullet that penetrates.

Bullets of identical non-deforming construction, shape, and sectional density, fired at identical velocity, will have identical penetration characteristics regardless of diameter. And it requires more energy to penetrate all the way through than only part way. Do you really believe a .22 Short to be more lethal. because all its energy would be used up in the target, than a similar 5.56x45 bullet that penetrates all the way though ?

[bennedose]

Bullets of identical non-deforming construction, shape, and sectional density, fired at identical velocity, will have identical penetration characteristics regardless of diameter. And it requires more energy to penetrate all the way through than only part way. Do you really believe a .22 Short to be more lethal. because all its energy would be used up in the target, than a similar 5.56x45 bullet that penetrates all the way though ?

No please. Do not confuse lethality with giving up of energy.

A bullet that passes through and makes a clean hole retains some energy as it flies out and fails to give up all its energy in the target.
An exactly similar bullet that perhaps hits some embedded hard structure and tumbles and fails to pass through gives up all its energy.

This is elementary physics and cannot be changed. In neither case does the target have to be an animal. It could be a bundle of cloth or a lump of silicone.

Lethality is a completely different issue. Lethality is determined by the manner in which energy is absorbed by tissues and which specific tissues absorb the energy. Not by size or energy of bullet.

I do not want to talk about lethality simply because it introduces yet another variable for this thread. The variables I am talking about are
1. Design of air weapon for military/police
2. Characteristics of bullet/pellet
3. Conditions that increase the possibility of lethality

The last is least relevant to the topic.

[Vikram]

Bennedose,

Heard of Quakenbusch air rifles used for big game hunting? Check them out and let us know if they fit your requirement.

Interesting exercise but I honestly do no think that they could really be a viable alternative to firearms. Silence, range, energy, cost of production, flexibility and reliability- you name it, firearms have edge over air rifles. I would be glad if I am proven incorrect in my opinion.

Best-
Vikram

[bennedose]

Bennedose,

Heard of Quakenbusch air rifles used for big game hunting? Check them out and let us know if they fit your requirement.

Interesting exercise but I honestly do no think that they could really be a viable alternative to firearms. Silence, range, energy, cost of production, flexibility and reliability- you name it, firearms have edge over air rifles. I would be glad if I am proven incorrect in my opinion.

Best-
Vikram

Vikram I have posted a link to Quackenbush on page 1 of this thread. I found it while searching for information.

Your view on this may well be right, but the point of the exercise to to try and examine the theoretical limits of what can be achieved.