my understanding from the sources and my local experts is that most of the peruvian 91s went back to europe and were returned with lange sights. due to change to spitzer bullet. so some with ladder sights exist but are rare having escaped the refurb roundup. is this why there are no peruvian 09s with ladder sights? how does sight type, bullet design time of build/use influence the fact that no argentine 91s,and i assume no bolivians, have only ladder sights?