Hoot has a great idea for using a spring punch to mark brass for number of reloads at the case web. However when I tried it I found it a bit tricky to keep the brass from spinning when trying to punch it. This really slowed me down on the first batch of cases and resulted in a couple gouges instead of nice pin marks.
My solution to this was to build a jig to hold the case and guide the punch onto the case web. Pretty simple taking a hard block of wood, in this case some scrap popular. Drill a 1/2 inch hole about 3/8 down (to far down and the punch bottoms out before it completes the spring cycle) from top to depth of about 1/2 inch.
Insert a case and mark it where it comes out of the hole. Using this marked case as a guide put a mark on the centerline where the web will line back from the face. Drill the intersecting hole with a drill same diameter as the punch shank. This should give a guide hole that puts the punch point right on the case web. Now I can mark 50 cases in just a couple minutes. For a visual see the attached pictures.