AR10 i need to remove a castle-nut, but I don't have the wrench. Ideas? (besides buying one, I don't want to wait)?

You can go to a plumbing supply store and buy a 'spline wrench' - these are use to remove the big caps on large conduit. A cheaper solution would be to use a rubberized strap wrench.

However, you will always be unhappy. In my 40 years of working and building AR for military and competition - that castle nut on carbines...... if you do not use the right tool that bastard will always, always, always come loose unless you do something stupid like Locktite it.

Just take it to a real gun shop ...........buy something, a box of ammo or something you can use so the shop makes a 'sale' and then ask to borrow the wrench.

You could do what some of these 'professional' semi-trailer mechanics do. Take a chisel and a BFH and drive the nut around in the direction you want.

Your question makes me cringe when I hear an alternative to using proper tools vs improvised methods.

However, I will show you the ropes so pick a tool that looks familiar to you. These tools vary from redneck to professional....try your luck...I`m curious as heck.

NOTE: All the shown except one will remove the castle nut..can you pick it out? The inch-pound torque wrench doesn`t count.