It goes fairly fast,,the wriggle cut as it's called. You are using a graver the width of the rib and walking it or rocking it in motion edge to edge of the tool as you go down the rib. It leaves an V pattern on the steel. Take a look at the borders on Browning A5 shotguns and Parker V grades,,those are done in this manner.
How tight depends on the speed you go and the angle to the work. Keeping things in control a very even pattern can be done. Then go back and do the same from the other direction crossing the V's and forming an X pattern.
MAkes a nice rib matting and was used quite often.
Another way is to go accross the rib back and forth but that takes more practice to keep things from getting out of wack and from jumping off the rib and stabbing the bbl.
You can 'florentine' the rib with a wide liner graver. Tedious but it looks nice. Go up from both sides at about a 45* angle accross the rib. Penciled guide lines keep the cuts at the same angle as you work or you'll get these out of sorts too.
By hand or w/hammer & chisel, it makes a nice rib surface.
The last one I did in this manner took me about an hour on each side, 2 hrs total to complete on a rifle bbl top rib, 26" length.
