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Author Topic: Bolter rifle specs  (Read 16274 times)

Societal Eclipse

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Bolter rifle specs
« Reply #15 on: September 13, 2006, 06:48:49 am »
Quote from: "Rani"
What you *could* do is fire the ammo
fast enough it will be almost uneffected by recoil
[the bullets leave the gun before the gun is moved by
the recoil]

See for example the [real life] "metal storm" gun.


http://world.guns.ru/assault/as42-e.htm
See this for another real world example.

Quote
But, when firing the three-round bursts, second and third cartridges are feed and fired as soon as the chamber is ready for it, and third bullet leaves the barrel PRIOR to the moment when the housing becomes to its rearward position. This results in wery high rate of fire with three-shots bursts - ca. 2000 rounds per minute. Also, this results in that the actual recoil affects the rifle AFTER the last bullet in the burst is fired.


This gun used caseless ammo with the bullets glued to the explosive charged like in Metal Storm.  I imagine with the projectiles firing 2-3x as fast it would be even easier to get a burst off before the recoil effects the soldier.

mocker

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Bolter rifle specs
« Reply #16 on: September 13, 2006, 07:23:26 am »
Bullets break the sound barrier and make a distinct noise doing it. When a rifle is fired the sound consists of two components, the explosion that launches the bullet (a boom) and the sonic boom of the projectile breaking the sound barrier (its a very sharp crack or crisp snap). A .22 long rifle is right on the edge of this phenomena. If you fire it from a rifle, its velocity is supersonic and you get the crack. If you fire it from a semi-auto pistol, the velocity is slower than the sound barrier and you don't get the sharp crack.

What you hear down range is a little more complicated. The first thing you'll hear is the bullet whizzing or zinging past. If it's still traveling faster than the speed of sound, I  think you'll get a sonic boom off it rather than a "zing." Then you'll hear sonic booms from further back along its path, all the way  back to the weapon firing as soon as  each noise reached you ... there is a sniper scene in the Private Ryan movie that depicts this.

Silenced guns slow the bullet below supersonic and also muffle the boom of the explosion. All that's left are the mechanical clicks that come from the mechanical movements of the gun.

Your hypothetical hypervelocity magnetic gun wouldn't have the chemical boom. No moving parts, so no mechanical sounds. Maybe a cool electric whir if you want. The sonic boom would be heard. I think it would be like a supersonic jet ... the bullet goes past and you get a sharp crack followed by less sharp sounding ones as the earlier sound waves reach you attenuated by distance, but I'm not sure.

Two other things that affect weapon accuracy are barrel heating and vibrations. The gun barrel heats up and the barrel bends a little, changing your aim point (the first shot is right on but the others aren't). I think you'd still get this from friction because of how fast your bullet is. Likewise the gun going off is like ringing a bell and the barrell vibrates again shifting the aim point (this affects every round) ... I think you'd also get this from the motion of the bullet in the barrel (like stroking the edge of a wine glass). Either one can make the gun significatly less accurate.

There are various tricks that are used to reduce the effects of recoil on the shooter. The most effective is to direct the gasses leaving the barrel in a convenient direction. Pads, springs, and etc. add weight and steal bullet energy but reduce bruising.

The game issue I'm curious about is how the bolter difers from a sniper rifle. I think for the same energy heavier bullets penetrate better than light ones (the v^2 thing), so maybe the bolter could be better against light armor and the sniper rifle better against the heavies?

grumpy

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Bolter rifle specs
« Reply #17 on: October 16, 2006, 09:51:02 pm »
Quote
What you hear down range is a little more complicated. The first thing you'll hear is the bullet whizzing or zinging past. If it's still traveling faster than the speed of sound, I  think you'll get a sonic boom off it rather than a "zing." Then you'll hear sonic booms from further back along its path, all the way  back to the weapon firing as soon as  each noise reached you ...


From experience it sounds like a crack and echoes, no whizzing or zinging that I remember, and it gives the unnerving feeling that you don't know where it came from. The zinging you get when the bullets hit something and ricochet or tumble in different directions.

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Your hypothetical hypervelocity magnetic gun wouldn't have the chemical boom. No moving parts, so no mechanical sounds. Maybe a cool electric whir if you want.


A rail gun gives off an enourmous noise when fired, but a coil gun probably would not. On the other hand, both would have to be extremely rigid not to give off som mechanical noise when fired. Transformers in power supplies are commonly dipped in glue or varnish to prevent them from vibrating due to the magnetically induced forces. I think it's called magnetostriction.

Quote
There are various tricks that are used to reduce the effects of recoil on the shooter. The most effective is to direct the gasses leaving the barrel in a convenient direction. Pads, springs, and etc. add weight and steal bullet energy but reduce bruising.


Not sure what you mean here. Viscoelastic or rubber pads are used to spread the recoil force in time, i.e. reduce impulse. The mechanism of automatic or semi-automatic guns use some of the gas pressure to move the bolt and reload the gun.

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The game issue I'm curious about is how the bolter difers from a sniper rifle. I think for the same energy heavier bullets penetrate better than light ones (the v^2 thing), so maybe the bolter could be better against light armor and the sniper rifle better against the heavies?


Depends on the armor, the bullet and the velocity. A small fast bullet delivers more energy to the target than a large slow one. To penetrate a hard shell armor you would probably want a fast high density projectile with a small cross-section. The same would probably apply to the fabric of kevlar or similar body armor. Maximum energy transfer per area to punch through the shell. To penetrate something softer, for example shooting at someone that is under water a slow heavy bullet should work better. At high velocities all objects appear as a hard surface, assault rifle bullets can shatter when they hit water for example.
As a comment, it is easier to hit a target at long range with a faster bullet. This is both due to that the trajectory is flatter and that you don't need to lead a moving target as much. However, light bullets are more easily affected by wind, rain etc.

grumpy

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Bolter rifle specs
« Reply #18 on: October 19, 2006, 01:49:46 am »
I modified the old description in the wiki according to some of my ideas. I copy it here as well and would appreciate comments. I did not intend everything in the description to be implemented in the game, but rather to give an atmosphere to it.

[quote Draft]The MkII Electromagnetic Rifle launches a small magnetic alloy projectile at medium hypersonic velocities to produce a kinetic kill on most targets. Tests with high-density penetrators against armor have shown that the MkII can penetrate the standard armor of most light and medium tanks currently in use. However the secondary damage induced would probably not be enough to disable the target without multiple hits on vital systems.

The MkII is designed around a superconducting linear accelerator operating in a low pressure inert gas atmosphere. The new generation of switchable high temperature superconductors has made it possible to realise some theoretically sound but previously highly inefficient designs dating from the early years of research into EM accelerators.

Due to the limitations imposed by high power requirements and the external environment, the MkII accelerator is operated in an underpowered mode. If operated at highest acceleration the projectile either fragments explosively or is turned into a hypersonic particle stream when exiting the barrel into air at atmospheric pressure. The recoil at that setting with the current projectile would also be significant. Underpowered operation also allows higher burst repetition rates by reduced cooling requirements.

The projectile is smaller and lighter than the standard projectile used in the AR-80 assault rifle. The current design uses a composite projectile with a penetrator consisting of a high density magnetic alloy core surrounded by a low density ceramic shell for ablation resistance and increased effect on soft targets, trading armor penetration and range for tactical flexibility. The magazine incorporates a small inert gas supply and and a high capacity storage capacitor. Care should be excercised in handling of spare ammunition in the field, since a breached or overheated storage capacitor will turn into the high-tech equivalent of an incendiary grenade.

The EM Rifle has no moving parts, and is therefore silent apart from the sound of the projectile as it breaks the sound barrier. Despite heavy shielding, the switching of the superconductors in the MkII rifle has severe effects on electronic equipment in the vicinity when fired, especially in the direction of the target. Non EMP protected electronic equipment within a 2m radius or 5m in front of the gun will risk permanently reduced performance or burn-out. [/quote]

grumpy

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Bolter rifle specs
« Reply #19 on: October 20, 2006, 08:24:07 pm »
Brainstorming a bit more...

An idea to depict the firing would be a fast, slightly glowing, bullet followed by a quickly dispersing vapor trail. Imagine a miniature meteor moving horizontally...

Offline Winter

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Bolter rifle specs
« Reply #20 on: October 24, 2006, 07:26:52 am »
Quote from: "grumpy"
Brainstorming a bit more...

An idea to depict the firing would be a fast, slightly glowing, bullet followed by a quickly dispersing vapor trail. Imagine a miniature meteor moving horizontally...


If you want to brainstorm with me and preview articles that are not yet on the wiki, please come to the #ufo:ai IRC channel in freenode.net. I could use a few more knowledgeable feedback voices.

Regards,
Winter

grumpy

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Bolter rifle specs
« Reply #21 on: October 24, 2006, 10:35:06 pm »
Quote from: "Winter"


If you want to brainstorm with me and preview articles that are not yet on the wiki, please come to the #ufo:ai IRC channel in freenode.net. I could use a few more knowledgeable feedback voices.

Regards,
Winter


My firewall is driving me nuts, but I'll work on it.