I expect I'm in the minority, but after a lot of years of playing with air rifle, rimfire and centerfire benchrest shooting, here is my opinion, and it's worth your cost. I put measuring pellet head size in the same category as weighing pellets or rimfire cartridges, measuring rimfire cartridge rim thickness, or, in the case of CF, measuring bullet diameters or weights. These are all variables that affect performance, no doubt. But, keeping it in perspective, does it matter as much as simply choosing a good pellet for your rifle and practicing with it? In my opinion, it does not. My advice, practice as much as you can, sip a good Kentucky bourbon (not while shooting), and don't get too distracted by the tedium, until you reach the top tier of world class shooters .