I have a 177 pellet gauge. I bought it when I was trying to figure out why one tin of Crosman 10.5 grain shot great and the next two shot poorly. It gave me the reason. The "good" tin was pretty consistent in head diameter and the "bad" tins were all over the place. Some pellets were in each of the 10 sizes of the gauge - or beyond. I also learned that H&N "match" pellets have more consistent head diameters than non-match Baracudas. Kind of pricey way to find out these things but I like to know why things work.
I now have a gun that likes H&N Baracuda 18s, a Air Maks Caiman. It shoots them better than JSB 18s or one other 18 I tried that I am forgetting now. But I get occasional 9s and 8s at the 30 yard challenge with them. My prior 177 experience makes me wonder if at least some of these may be a pellet with a different head size. So I will sort them and see if it makes a difference. I will probably try and figure out if the one tin of JSB 18s I have is more or less consistent than the H&N 18s too. Or if the JSB are a different head size than the H&N helping to explain the gun's preference. I'll post what I find.
I now have a gun that likes H&N Baracuda 18s, a Air Maks Caiman. It shoots them better than JSB 18s or one other 18 I tried that I am forgetting now. But I get occasional 9s and 8s at the 30 yard challenge with them. My prior 177 experience makes me wonder if at least some of these may be a pellet with a different head size. So I will sort them and see if it makes a difference. I will probably try and figure out if the one tin of JSB 18s I have is more or less consistent than the H&N 18s too. Or if the JSB are a different head size than the H&N helping to explain the gun's preference. I'll post what I find.