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Difference between revisions of "M16 Rifle Series"

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http://vietnamresearch.com/weapons/M16A1.jpg
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Lightweight rifle, cal 5.56mm.  
  
The Colt M16 was developed from the AR15 Rifle designed in the late 1950s. It is fundamentally a scaled-down [[AR-10]].  The ArmaLite division of Fairchild Aircraft Industries, employed [[Eugene Stoner]] to design a new assault rifle for the US forces.  The AR-10 was the result, but Stoner sought a design which would lighten the infantryman's burden.
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Originally in service with the [[British Army]] in Malaya as the AR15, it was then adopted as the M16 by the [[USAF]]. It was type accepted by [[USMC]] and [[US Army]] after few modifications had been added, the most notable being the forward assist plunger.
  
Seeking greater hitting power, he redesigned a civilian (.222" Remington) hunting round.  Giving it a longer case (and therefore a heavier charge) he renamed it the .223" Remington. It delivered its 55-grain projectile at a muzzle velocity of around 3250 feet per second.  The rifling imparted just enough spin to stabilise the bullet in flight.  On contact with a solid object, however, the bullet would topple, delivering maximum energy to the target.  The design team of Robert Fremont and L. James Sullivan then set to work to make the weapon itself - the AR15.
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Designed by Eugene Stoner, manufactured by Colt and later [[FN]]. Never manufactured by Mattel, contrary to popular belief.
  
When the [[USAF]] employed South Vietnamese Army ([[ARVN]]) troops as Airfield Defence Guards in [[Vietnam]] in 1963, they equipped them with their new lightweight assault rifle, by then known as the M16. The weapon proved very popular with the [[ARVN]], whose light-framed soldiers found the then standard [[7.62mm]] [[NATO]] M14 heavy and cumbersome. After trials and evaluation by the [[US]] [[Special Forces]] in South-East Asia, the weapon was adopted by the US Army, and has continued in service ever since. 
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Rotating bolt, considered a 'dirty' weapon because of the direct application of the gas to the bolt without the use of a piston, i.e. it shits where it eats. Originally designed to be a .223 Remington calibre, it was re-designed to take the NATO standard loadings, which are a slightly higher pressure although of practically identical dimensions ''(in practice, there is no difference between .223 Remington and 5.56 NATO, the difference being in the permitted cartridge overall length and permitted maximum pressure, and certainly no redesign took place for the nominal change - Stoaty)''
  
The whole concept, with extensive use of aircraft-grade aluminium alloy and plastics in its construction, was designed to save weight.  Even the beefed-up .223" ([[5.56mm]]) round was considerably lighter than the [[7.62mm]] round.  There was no gas-piston:  gas was tapped into an above-barrel gas tube, entered a doughnut shaped chamber formed between the bolt and the bolt carrier, the expanding gas driving the bolt carrier backwards in order to achieve extraction and reload. The non-reciprocating cocking system meant that a "forward assist" plunger was required in case the bolt failed to seat after cocking.
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Upon initial service entry, it attained a reputation for unreliability. This wasn't the fault of the design as much as the fault of the Army trying to cut costs by using a lower grade and dirtier propellant, and also myths such as 'The M-16 never needs cleaning.'
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The original 'waffle iron' magazines also contributed to the reliability problems.
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Eventually these problems were rectified.
  
Extensive sales to South American and South East Asian armies, plus contracts with the US armed forces, kept the production lines open through the 1970s into the 1990sIt outsold the [[Europe]]an [[7.62mm]] rifles in these markets, despite its relatively short service life compared to the more robust FN FAL.  The Israeli Army adopted a carbine version for its Special Forces, and the CAR15 weapons system in service today, is much prized for its versatility.   
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The M16 and M16A1 had smooth triangular hand guards, (constructed in left and right hand halves,) and was select-fire between semi-auto and full auto using a three-position safety/selector switch, manipulated with the firer's thumb. The M16A2 incorporated a number of changes:
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*  New flash hider without slots on the bottom to reduce signature by dust or sand being blasted up on firing.
 +
*  New foresight blade, (five positions per rotation,)
 +
*  New bbl which is thicker in the visible section beyond the hand guards and has faster one in seven twist to stabilise the M855 projectile. (As opposed to the earlier one in twelve for the M193 rd.) The bbl retained the original outside diameter under the hand guards both to keep weight/cost down and so that the M203 clips could still be used.
 +
* The round profile hand guards are ribbed and now fit above and below the bbl. The upper and lower halves are identical, thus reducing Log Sp.
 +
*  The rear sight was changed so that the firer can adjust both windage and elevation from this point, and also do it by hand as opposed to using a tool or bullet.
 +
*  A case deflector was added so that when firing from the left shoulder the hot brass doesn't scoot down the firer's collar.
 +
* The new pistol grip incorporates a groove for the Sunday-go-courting finger, and has vertical ribs down the back strap. (No, ''not'' for extra pleasure.)
 +
*  The full auto capability was replaced by a three rd burst facility to enhance hit probability and conserve ammunition. Unfortunately the rotary sear allows one or two rds only to be fired if the user releases the trigger before the burst has finished. This means that the next time a shot is taken the trigger pressure will be different - not conducive to good marksmanship.
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* The butt stock is slightly longer and the butt plate now hatched over the entire surface.
  
The current version on issue to the US Army is the M16A2 - basically a slightly-lengthened and strengthened version of the original. The [[Fiji]]an Army recently replaced their long-serving [[7.62mm]] [[L1A1]]s with M16A2s.  
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The latest magazines now have a larger anti-tilt follower, and this is also being retro-fitted to older mags.
  
http://www.fototime.com/E0479C00AB26227/standard.jpg
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The latest full-sized M-16 is the A4 variant, with the rear iron sight mounted on a picatinny rail so that it may be quickly replaced with an optical sight.
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The carbine version is the M-4, with a telescoping stock and shorter barrel with a distinctive profile where the forward 203 clip can be fitted.
 +
 
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The two major advantages of the rifle are the magazine change and adaptability.
 +
1.  The magazine is dropped free with the trigger finger, the replacement mag is inserted without any more manipulation and the bolt released with a slap.
 +
2.  The easily-replaced hand guards can have up to four mounting rails in addition to any on the top of the body. Many American soldiers have been known to place personally-owned items on their rifles, from Surefire lights and holographic sights through to the issued night vision devices or infra-red pointers.
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The [[5.56mm]] round is questioned by some in American circles because of a stated lack of immediate lethal effect. This may be a reflection on the lower muzzle velocity imparted by the shorter carbine which is in increasingly greater circles.
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Due to the inline layout all the AR15/M16 family are very controllable in full auto, any perceived problems are always attributable to incorrect firing positions.
 +
Those with shorter bbls exhibit more pronounced muzzle blast, but this is common to all short bbl rifles.
  
 
[[Category:Weapons]]
 
[[Category:Weapons]]

Latest revision as of 19:11, 21 March 2011

Lightweight rifle, cal 5.56mm.

Originally in service with the British Army in Malaya as the AR15, it was then adopted as the M16 by the USAF. It was type accepted by USMC and US Army after few modifications had been added, the most notable being the forward assist plunger.

Designed by Eugene Stoner, manufactured by Colt and later FN. Never manufactured by Mattel, contrary to popular belief.

Rotating bolt, considered a 'dirty' weapon because of the direct application of the gas to the bolt without the use of a piston, i.e. it shits where it eats. Originally designed to be a .223 Remington calibre, it was re-designed to take the NATO standard loadings, which are a slightly higher pressure although of practically identical dimensions (in practice, there is no difference between .223 Remington and 5.56 NATO, the difference being in the permitted cartridge overall length and permitted maximum pressure, and certainly no redesign took place for the nominal change - Stoaty)

Upon initial service entry, it attained a reputation for unreliability. This wasn't the fault of the design as much as the fault of the Army trying to cut costs by using a lower grade and dirtier propellant, and also myths such as 'The M-16 never needs cleaning.' The original 'waffle iron' magazines also contributed to the reliability problems. Eventually these problems were rectified.

The M16 and M16A1 had smooth triangular hand guards, (constructed in left and right hand halves,) and was select-fire between semi-auto and full auto using a three-position safety/selector switch, manipulated with the firer's thumb. The M16A2 incorporated a number of changes:

  • New flash hider without slots on the bottom to reduce signature by dust or sand being blasted up on firing.
  • New foresight blade, (five positions per rotation,)
  • New bbl which is thicker in the visible section beyond the hand guards and has faster one in seven twist to stabilise the M855 projectile. (As opposed to the earlier one in twelve for the M193 rd.) The bbl retained the original outside diameter under the hand guards both to keep weight/cost down and so that the M203 clips could still be used.
  • The round profile hand guards are ribbed and now fit above and below the bbl. The upper and lower halves are identical, thus reducing Log Sp.
  • The rear sight was changed so that the firer can adjust both windage and elevation from this point, and also do it by hand as opposed to using a tool or bullet.
  • A case deflector was added so that when firing from the left shoulder the hot brass doesn't scoot down the firer's collar.
  • The new pistol grip incorporates a groove for the Sunday-go-courting finger, and has vertical ribs down the back strap. (No, not for extra pleasure.)
  • The full auto capability was replaced by a three rd burst facility to enhance hit probability and conserve ammunition. Unfortunately the rotary sear allows one or two rds only to be fired if the user releases the trigger before the burst has finished. This means that the next time a shot is taken the trigger pressure will be different - not conducive to good marksmanship.
  • The butt stock is slightly longer and the butt plate now hatched over the entire surface.

The latest magazines now have a larger anti-tilt follower, and this is also being retro-fitted to older mags.

The latest full-sized M-16 is the A4 variant, with the rear iron sight mounted on a picatinny rail so that it may be quickly replaced with an optical sight.

The carbine version is the M-4, with a telescoping stock and shorter barrel with a distinctive profile where the forward 203 clip can be fitted.

The two major advantages of the rifle are the magazine change and adaptability. 1. The magazine is dropped free with the trigger finger, the replacement mag is inserted without any more manipulation and the bolt released with a slap. 2. The easily-replaced hand guards can have up to four mounting rails in addition to any on the top of the body. Many American soldiers have been known to place personally-owned items on their rifles, from Surefire lights and holographic sights through to the issued night vision devices or infra-red pointers.

The 5.56mm round is questioned by some in American circles because of a stated lack of immediate lethal effect. This may be a reflection on the lower muzzle velocity imparted by the shorter carbine which is in increasingly greater circles.

Due to the inline layout all the AR15/M16 family are very controllable in full auto, any perceived problems are always attributable to incorrect firing positions. Those with shorter bbls exhibit more pronounced muzzle blast, but this is common to all short bbl rifles.