In 2000, Z-M Weapons of Bernardston, Massachusetts (USA) developed a conversion kit for AR-15-based weapons to produced the "LR-300" tactical automatic weapon. The kit provided a revision to original AR-15-style assault weapons by revising the direct gas-impingement system so an all-new, side-folding adjustable skeletal stock could be used (replacing the M16-style cylindrical recoil buffer tube in use). These changes allowed for increased compactness of the weapon which is always an appreciated quality of some long guns. An optional length of Picatinny rail could also set above the upper receiver for support of tactical accessories such as optics and aimers. On the whole, the form and function of the AR-15 weapon remained largely the same though the kit's reception was met with mixed results.
Four major versions of the kit - two to serve the military / law enforcement market and two to serve the civilian / sporting market - were made available: The LR-300 ML-A was developed for military / law enforcement circles and included an 11.5" barrel assembly and selective-fire modes. Similarly, the LR-300 ML-N has an 11.5" barrel with selective-fire, optional Picatinny rail, and Nylatron forend (the latter replacing the aluminum forend). The LR-300 SR-A for the civilian market was a semi-automatic-only model with 16.5" barrel length. The LR-300 SR-N followed in semi-automatic-only fire mode and included the Nylatron forend and optional Picatinny rail.
The rights to the product were sold off to Para Ordnance in 2009.