Trying different bullets?

[wisconsinteacher]

I am going to try a different bullet in the 7mmRM and 338WM and have a quick question.

When changing over, would you leave the seating stem at the same place or would you start all over and determine the jump for each one?

I am going from the 150 CT B-Tip to Partition in the 7mm and from the 225 Interlock to the 225 AccuBond in the 338wm.

I plan on using the same powders but at different charges to start out with development.

 

[DrMike]

When changing over, since you have a different bearing surface, you are starting from scratch. You have already indicated that you are adjusting charge weights before working up, so that will not be a problem. You have to start somewhere, so there is nothing wrong with starting where you were previously. I would, however, start work on the Partition at 0.010 inches off the lands if the magazine allows. I would initiate work on the AccuBond at 0.100 inches off the lands.

 

[M7025-06]

For every bullet I test, I go through the whole process of figuring out the OAL to the lands for that specific bullet (using a Hornady Comperator) and write each one down in my log book.

I used to use a Hornady OAL gauge but I figured out that the modified case has a different headspace measurement than my fired brass for my rifle, so I just use an old piece of brass with the same headspace measurement as the rest of my fired brass.