Otacon· Premium Member
The ejector spring on a MR556/HK416 is a lot stiffer than your typical AR-15 ejector spring. The only way I could get it installed was to use a spent casing to push and hold the spring and ejector in and slide in a slave pin in the hole for the ejector pin. I used the hole in an armorers puck to hold the spent casing steady while doing this. Then I put the bolt into the Sinclair Bolt Vise and installed the ejector pin.