Just use the chart for the powder you are using. All the powder manufacturers have them redily available online. They aren't machined accuratly enough for a decimal chart, just in the ball park. That is one of the reasons why Mec bushings are so cheap compared to what Hornady, RCBS, PW, etc.
As for me, I'll stick with using what Hornady has to offer.
10tenner, I sent you an email that shows the bore diameter of MEC bushings in thousand's of an inch. Not sure if this is what you wanted, but email is pretty inexpensive. The chart was gift from another viewer of Trapshooter.com to me when I requested it a month or so ago. Great web site isn't it!!! Bob R.
Don I'm not saying your thinking is wrong. I feel more comfortable with a finer dergee of accuracy, That maybe because I've worked in machine shops for over thirty years. I'm acustom to spliting hairs all day. I've also found powders do vary from keg to keg. Maybe one bushing like a 447 to a 450 or a 444. Just my experence. Lou
The file I have is in Excel. When i copy and pasted, it didnt look the same. Not really a computer guy hehehehe I will send it to you by email. I got the file from a person here and I feel bad cause I forgot who sent it to me. I looked in my emails and guess I have cleaned house. I havent measured any bushing myself. Kind of like a powder chart... weigh your powder! I did weigh some SOLO 1000 and made note of what they dropped with the powder I have. Like you well know always check weights. Check your email I just sent it to you. It has 2 different sheets too look at.. one is Mec and one has Mec,PW and Hornady bushing mixed in order.