To add to the above post, with ammo brands that respond to rim thickness sorting, we have found that just grouping by thickness numbers has resulted in smaller groups, with a general tendency for group size to further improve as rim thickness increases, UP TO A POINT. Once that point is reached, groups with greater rim thickness don't show any increase in accuracy and sometimes fall off a bit. Generally, this spot has been reached about 0.040" if memory serves. To get much of any gain you have to sort a brick at a time to get significant quantities of each thickness, and in the few brands we have sorted, the biggest number has been in the 0.038", +/- portion of the range with a marked drop off in quantity of 0.040" or larger out of a 500 round brick - the number of cartridges in each 0.001" increment batch between 0.035" and 0.041" is pretty much a bell shaped curve in quantities of one or more 500 round bricks with the same lot number in our experience. For the ammo we shoot and the rifles we shoot it in, anything 0.035" or under, or over 0.041" becomes barrel foulers for serious shooting or plinkers for our fun shooting. As before, your experience may vary. Like anything to do with rimfire shooting, each rifle has its preference for optimum rim thickness, just as for ammo brand.