Ok all you AR-15 gurus. I have 70s vintage colt. The pivot pin is the type with a retaining screw in the left end of the pivot pin. The screw must be removed to push the pin out. Ive ordered a push button type, but then started thinking. Ill have to completely remove it to separate upper and lower rather than it staying in the right-hand ear of the lower like the take down pin does. Right? Also, since the rifle doesnt have a detent pin (in right the ear of the lower) I couldnt use a push-pin like some ARs are equipped with right?