Sunday, April 17, 2011

History and Development of the Assault Rifle - IV

In the last post, we studied the origins of the AK-47 and the beginning of the AKM. The AKM featured several improvements over the AK-47, mostly geared towards improving the production rate. In the initial AK-47 design, they had attempted to make the receiver out of stamped parts to speed up production, but the Soviets lacked the proper technology to do so and had issues with the resulting product. Hence, they resorted to machining the receiver from a block of metal, which was a slower process. However, in the 1950s, they used several captured German technicians to teach them metal stamping technology and hence the AKM featured a stamped receiver. Among the many improvements that the AKM had over the original AK-47:

  • Replacement of the milled receiver with a receiver made out of stamped sheet steel. Machining is a lot slower process than using a press to stamp parts. Hence, use of stamped parts made it much faster to produce AKMs.
  • Using rivets instead of welds on the receiver, in order to speed up production.
  • Improvements to barrel, gas ports etc. to speed up manufacturing and enhance reliability
  • Weight reduction of approximately 1 kg. (2.2. pounds)
  • Retains the chrome lined barrel and chamber of the AK-47 Type-2 variant, but the barrel is pressed and pinned to the receiver, instead of the AK-47 which has a threaded barrel that is screwed into the receiver.
  • The barrel is the first in the AK family to have a slant compensator to reduce rifle climb, when shooting in automatic mode.
  • Gas relief ports are moved forward to the gas block, instead of the gas tube.
  • Bolt carrier was lightened slightly. The wooden stocks were also hollowed out as well, in order to reduce more weight.
  • Sights on an AKM are calibrated to go up to 1000 meters, whereas AK-47s are only calibrated to go up to 800 meters.
  • Changes to the metal treatment applied. The AKM is parkerized instead of blued like the AK-47.
  • Uses modified spring and trigger assembly for better safety. The AKM fires in automatic mode only when the bolt is fully locked. The new trigger assembly also reduces "trigger bounce" and has a hammer release delay device to delay the release of the hammer by a few microseconds in automatic firing mode. The hammer release delay mechanism is sometimes incorrectly called a "rate reducer" by some people, but it doesn't appreciably change the cyclic rate of fire. Instead it allows the bolt group to settle in the forwardmost position after returning into the battery.
The Soviets made millions of AKMs and they weren't shy about handing out the plans to other co-operating countries, so that they could make their own as well. This is why AKMs are so widespread around the world.

AKM assault rifle. Click on image to enlarge. Public domain image.

The basic AKM design also has a number of variants. Some of these are:
  • AKMS - This is one of the commoner variants of the base AKM. The AKMS features a metal stock, which is foldable.
  • AKMP - This variation uses tritium front and rear sights for better visibility in low light conditions
  • AKML - This variant has a side mounting rail to mount a night vision device.
  • AKMLP - Same as AKML, but also has tritium sights as a backup.
  • AKMSP - Same as AKMS, but fitted with tritium sights
  • AKMSN and AKMSNP - Same as AKMS (i.e. foldable stock), but also has a side mounting rail to attach a night vision device. The AKMSNP version also has tritium sights.

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