Hot on the success of the CMMG Mutant, Palmetto State Armory released their 7.62×39 AR hybrid, instead opting for compatibility with the AR-15 platform versus its own proprietary system. Originally shown at SHOT 2016 and shot at the Big 3 East in the spring, the KS-47 has begun shipping and now with bare receivers available, is now the subject of some compatibility issues.
As PSA stated in their videos released at Big 3, the lower is (paraphrase) “compatible with other companies 7.62×39 upper receivers,” which while factually true in terms of their pin placement will have a functional issue. The root cause is the combined usage of an AK-47 magazine and a “standard” AR-15 upper. The AK magazine has wider and taller feed lips compared to the STANAG pattern.
When attempting to mount a “standard” 7.62×39 upper to a KS-47 lower, the feed lips of the AK magazine interfere with both the receiver itself and the bottom of the bolt carrier group (though the bolts do clear). As such, mounting a “standard” receiver is not possible without having a machine tool to mill the sides of the receiver and bottom of the bolt carrier group.
That said, receivers specifically designed to handle the AK magazines will work. Options from Michael’s Machines, MGI, and others are typically drop-on compatible.
PSA has intimated that they will be offering their upper receiver as a set in the near future, but home-builders and dreamers should ensure they have compatible options / machine tools prior to the building process.