ironruger,
If your 15-22 has the bird cage flash hider you will need to remove it in order to take the quad rail end cap off sos you can use the barrel nut wrench. The crush washer at the rear of the flash hider will need to be replaced when reinstal it. A better option would be to use a peel washer as it's reusable.
Get or make a vice jaw clamp to hold the barrel before working on the flash hider or barrel nut or you will buger up the upper receiver when the barrel spins.
Smiling Bob
