I know this has probably been discussed time & time again.  However, search routine turns up nothing.

What tool are you guys using to adjust the front sight?  Tried a round.  It works ok, but awkward and leaves copper marks.

Thanks

If you have the square cross-section front sight post, make a "little socket wrench" from the handle of an old tooth brush or even a small diameter wooden dowel about 3" long.
Cut the tool flat on one end, and drill a 1/16" hole about 3/4" deep down the center.  Then take a square swiss file and plung it repeatidly into the round hole you drilled until the round hole is square and big enough to engage the top half of the front sight post.  This re-shaping works best if the file is held in a bench vise and the tool is plunged onto it back and forth.
Then on the range all you need in addition is a small pointed thing to depress the detent.
With a front sight turner like this, you can also easily switch from one sight post to another in seconds.  

The ready made round FS tools work ok but I found out that even the A2 tools have a round hole that sets down over the sight post and doesn't fit the square A2 sight posts very well. I drilled out the hole a little to fit over the A2 sight post and they work great now.

Been using a round. No problems, no copper. Always available.