We have one current semi-automatic alternative for donor parts to the manual action receivers. The combination of the WX-MCR receiver and proprietary parts kit will allow the use of the butt stock, pistol grip, trigger, and magazines, and bolt from a donor rifle; the handguard may be donated if it has enough height for the piston system, and the barrel can be donated, but only if it has a carbine length gas tube port (though this may change if longer Op rods are produced by a third party like True North Arms). The combination of having to separately source the proprietary parts kit and not being able to use all barrels and handguards have made this option not entirely popular, however.
Sylvestre Sporting Goods will be importing the Jard J180 Builder kit in late June to mid July. If the quality is improved over previous Jard offerings, this may prove to be a more palatable semi-automatic place to put donor parts then the WX-MCR kits. The firearm uses a standard AR gas tube to the receiver, and the use of multiple gas system lengths and their associated barrels may be possible with the assistance of an adjustable gas block. The use of a gas tube instead of of an over barrel pistol also means almost any standard AR hand guard should work. The wider parts compatibility, addition of an optional dust cover, closer overall appearance to a traditional AR may make it a good home for donor parts. Only time will tell if the design and build quality of the build kits will allow them to be both reliable and popular.
