Richardo,
You may be correct depending on the pellet that you are measuring, but that is not the norm. I measure H&N pellets almost exclusively, and all models, (Sniper lights, Sniper Mediums, Barracuda FT's, and Field Target Trophy), and all these models measure through the largest of apertures on the Pelletgage. This physically leaves no apertures left to measure the head size. I have also found that JSB Exacts, and Air Arms a little smaller in head size, but the apertures are still too small to measure skirt size.
I guess you have found the pellet that works for you, if I had to guess, on the smaller size on the Pelletgage, allowing you to use the larger apertures to measure skirt size as well. Good for you, good luck, hope it keeps working for you, but keep in mind, yours is a rare case. This is definitely not the norm, and I'd like to hear from others that can have this same thing apply to their pellet sorting regimen as well.......I find that all this stuff so interesting, and I think the only thing holding most guns back, in accuracy is the pellet. Anything and everything we can do to squeeze whatever accuracy we can out of our individual rigs is worth it.
Tom Holland