Originally Posted by
eodinert
I replaced the horrific take down pins on a HK MR556 without removing the end plate or castle nut.
I have found that a dental pick and a spare take down pin make it pretty easy. Once I've removed the old pin using the dental pick to push the detent into the receiver, I hold the spring and detent into the cavity using a small screw driver (or chopstick), and press the spare takedown pin in the hole from the wrong direction (taking care that the slot in the take down pin will not line up with the detent)... that holds everything in place. Next, I pushed the new take down pin in from the correct direction, taking care to make sure the detent pin track was pointed the correct direction, and push out the other pin. I rotate the new pin to make sure the detent is in the track, and drive on.