I also did the penny adjustments on my primary, and you are correct that they are not all the same. Pennys made before 1983 weigh 3.11g ( googled it, it’s true) I did weigh each one I used to make sure they were the same, all were newer ones at 2.5 g which was perfect to make all my weights 15g when I added 2. After putting some miles on I decided it grabbed a little low so I did remove 1 from every other one and now I think it’s perfect, so if you do the math ill need 13.75g weights, so I think I’ll be looking to get a set of weights so they all match, you made a good point, thanks