I did use their lpk. Some have made it happen without but sounds like pins are not standard and the bolt catch is different, seems like everyone was filing on an AR-10 B model catch to make one work. For the money I decided to go with their kit, just used a different trigger and grip. 98 pieced his together with stuff he had, I had an extra pivot pin in my kit which just happen to be the one he didn't have in his bin.