Chicken or The Egg... Again

[BillR]

A lot of it depends on the gun's magazine OAL and the length of the throat. I have some guns that have throats long enough that the bullet will drop out of the case before they touch and some that are very short throats. The short ones are east and I usually start those touching and then work back as needed and when I find a OAL the gun likes I will then play with the powder etc. to wring out the best accuracy I can.
The ones with the long throats I just load to the longest length I can for the magazine and work on load. My 700 VSF in .308 is like that. With the 175 SMK's though it does not seem to matter much where I load the bullet as it shoots great using the mag length even if the throat is long. What does seems to make a difference with it is neck tension.

[flashhole]

Once I select a powder to use I always try and find the optimum charge range where minor deviations in powder charge weight have mimimal to zero impact on point of impact. I try and key in on a charge weight that lets me use my Lee Dipper Cups instead of an adjustable powder measure (I find it faster and easier). I do this using COL data from the loading manuals. Then I tweak my seating depth. Once I find the seating depth I make a dummy round that I use to adjust the seat die between loading sessions.

It doesn't always work cleanly because if you start with a bullet your gun just doesn't like you burned a bunch of components. But, when it does work, it is very repeatable over long periods of time. As an example, I couldn't get 55 grain bullets to shoot worth a darn in my 223 no matter what powder charge I was using. Switched to 40 and 63 grain bullets and all was good. I burned through a bit of powder and primers before I found the better (for my bullets.