I just use a black Sharpie marker and make several "x" marks on a piece of paper (back side of any target, 5x7 index card, paper plate brown paper bag etc.).

Makes it very easy to put the reticle intersection into the "X" mark on the target for a very consistent/ repeatable for group testing. Low cost too.

"Behavior accepted is behavior repeated."

"Strive to be underestimated."