Published on February 8, 2025
Tom Gaylord:
Pellet head size
"I've known for decades that pellets come in different head sizes, because 10-meter ammunition is sold that way. I always assumed the number on the tin was the exact head size, and I had no desire to measure pellets because of the difficulty. Then Jerry Cupples came up with the Pelletgage idea, and the rest is history. I’ll be honest about this. At first, I thought Jerry was being too nitpicky with his idea that pellet head size is critical. I say that because when a pellet passes through a barrel, the barrel automatically resizes the head and skirt. But the first test I conducted in Part 2 of the report showed me just how important head size really is. If you follow that link and look at the targets, you’ll see what I mean.
"Having tested the Pelletgage many times (now in all four small-bore calibers), I no longer have the slightest doubt that pellet head size is a significant factor when it comes to accuracy. If you want to be as accurate as possible, you need to shoot pellets with the proper head size—and you can't rely on the pellet tins to tell you which ones they are."
http://www.pyramydair.com/blog/2016/12/what-is-accuracy-part-2/