grooves are cut with a tool, you will see tool marks the full length of the barrel in the grooves, running
length-ways of the barrel. The reamer marks will still be visible on the top of the lands.
In most cases you can simply remove the bolt and get a suitable light. Look through the barrel from the
muzzle end and be able to see what type of rifling it is.
In cut rifling the barrel is just reamed, then the rifling is cut into the bore, and this reamed surface shows
to be quite rough when magnified.
The top of the lands in conventional rifled barrels is covered with circular tool marks. These are
approximately at right angles to the motion of the bullet.
They tend to wipe off metal from the bullet and create high friction and barrel fouling. The surfaces of
the grooves, having been cut out by single tools or broaches moving in the same direction as the bullet
will move, have tool marks, which are rough, but will usually not create anywhere near so much friction.
Also after it is shot a while will very seldom foul up.
So knowing this it is obvious that the smoother the inside of the barrel, so far as friction and metal
fouling are concerned, would be the widest possible grooves, and narrow lands. There is a trade off on
this theory however, as the narrow land, is more prone to wear excessively, and to erode at the throat.
So we have to make a compromise and keep the lands wider to attain good barrel life. It can therefore
be said that button rifling and button burnishing of bores leave both land and grooves far smoother than
any finished reamed bore with grooves cut from it.
Button rifling has lead to new designs of rifling. Many shallower grooves may have advantages, or some