The Interdynamics MKR was a Swedish prototype assault rifle developed in the 1980s. The weapon never proceeded beyond prototype stages.

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The Interdynamics MKR was originally designed using a 4.5×26mm MKR round using solid copper bullets. Its purpose was to provide a flat ballistic trajectory along with armor-piercing capabilities with low recoil for the user to handle, even when fired fully automatically.

It was to use low-cost ammunition. The 4.5×26mm MKR round was claimed to be ballistically as effective at 300 meters as the 5.56×45mm NATO round.

It was a bullpup design, which means that the magazine is located behind the trigger, and utilized the blowback system of operation. The bullpup design made the firearm smaller and lighter.

• List of bullpup firearms
• List of assault rifles