" A sporting version of the PSL, intended for export, is offered as the PSL-54C, Romak III, FPK, FPK Dragunov or SSG-97. This weapon is identical in almost every respect to the original military version of the PSL except for modifications to comply with the U.S. import laws regarding sporting rifles. These modifications include removal of the bayonet lug as well as the replacement of the original military receiver, which has three trigger mechanism axis pin holes instead of two. The third hole is for a safety sear that is thought to allow the rifle to be capable of being converted to "full-auto" by the end-user. US import versions are manufactured with a BATFE approved semi-auto Romanian receiver. The so called "third hole" is not present, thus the trigger mechanism is simplified and omits the "full auto" safety sear. The military spec FPK is not capable of fully automatic fire however it includes this safety sear to ensure the rifle's hammer cannot be released before the bolt is fully forward and locked in place in the forward trunnion. Because of this fact, and the lack of a spring-loaded firing pin, there is some theoretical potential that the US legal PSL could fire out of battery (before the bolt is fully locked). The US commercial-spec rifles also sometimes omit the bolt hold-open mechanism that is on the true military spec rifles."..... From wiki .