An elegant solution - Wilson Combat Extension Tube Washer

Remington cha fed the design of the barrel nut many years ago. They removed the spring loaded decent that used to hold the cap (or mag extension) onto the shotgun. That causes some issues keeping mag extensions on the barrel as you loaded the shotgun. The compression of the spring and vibration would loosen the mag extension in many cases. This washer does a good job of keeping the mag extensions tight on a shotgun without the detent. It’s an inexpensive solution that works quite well.