I tried this early on with the 25g ammo (that was all I had at the time). I weighed it in grams just because my scales gave me weights to three decimal points using grams. I also weighed spent brass after shooting and found that even though sorted by weight, the brass often varies also. So, while the biggest variable is likely still the powder charge, sorting by weight still does not eliminate all flyers. In fact, sorting by weight did generate some tighter groups, of three shots each but when attempting to print groups of 5, I almost always got a vertical flyer that was usually lower but sometimes higher as well. There will be variation in brass weight, primer material weight, bullet weight (this is likely the most consistent variable) and powder charge weight. Weighing the cartridges can improve results some, but is not going to result in amazing results either. It take a lot of time, but hey, why not?

I have not tried it with the 20 grain ammo yet, but have finally obtained some, and also found that my gun does not shoot it as well as the 25g ammo. I am a reloader and learned that when I loaded lighter bullets toward the limits of the cartridge, that I often saw increases in the std deviation, and loss of accuracy. This is due to the limits of my ability to measure powder charge was about one tenth of a grain and one tenth grain variation with a lighter bullet causes more variation in velocity than it will with a heavier bullet. So, it is harder to get accuracy when using the same loading process. Therefore, the lighter, faster ammo is almost always going to be less consistent and usually less accurate, unless a certain gun's natural harmonic frequencies happen to match up to the lighter ammo's characteristics.

We found that most 17 HMR guns also shoot the heavier ammo better than the lighter bullets. Likely for the same reason, the heavier ammo has slightly less velocity variance.

Irish