[ccyg8774]

I used a method of tightening the URX handguard without special tool.
First remove the side bolts and remove the lower portion of the handguard.
You should be able to see the "ring" with 4 slots on it.
Try turn the handguard with your hand, you should be able to tighten it but it won't align right when it is tight.
Turn the handguard in the other direction so you will loose the handguard even more.
The "ring" is very loose right now, so you can tighten it a little bit (not all the way) by push the slot on the ring with a flat head screw driver.
Turn the handguard back so it will be tight. You may (or may not) have to keep the screw driver on the slot, pushing gently as you turn the handguard. Only pushing to make sure the ring is turning with the handguard or you may over tighten it.
You may have to go back and adjust the ring several times to get the right tightenness at the right alignment, if you over tightened the ring at any stage.
After you get it perfect, maybe... Put some removable threadlock on it? I didn't have any threadlock the last time I tightened my URX. I will try it next time.

This method have been tested on CA25 URX and DBOY SR25 URX.