I get asked now and then “Why doesn’t Windham Weaponry stake their castle nuts on?” The reason we choose not to is because many people want to upgrade some part of the stock, usually the endplate, and this requires loosening of the castle nut and removal of the stock. It’s much more difficult to do this if the castle nut is already staked on. The factory torque of our castle nuts is generally tight enough not to loosen under normal wear and tear, but if you feel that you would like to stake your castle nut on to make sure the nut never backs off, it is very easy and takes less than 3 minutes. Here’s how:
First make sure weapon is unloaded!
Push in takedown and pivot pins and remove the upper receiver from the lower receiver.
Now with the lower on a non-marring surface, take a center punch and a hammer and punch the end plate in the areas shown. That is what the little square cut outs are for in the castle nut, pictured below.