Thread: Gordon's Reloading Tool - barrel length question

Hi All, Couple of quick questions on using GRT.

How should barrel length be measured for input into GRT? Found a thread that says it should be the distance from bolt face to the crown. That would mean I have a 26in barrel when i thought I had a brand new 22in barrel. Obviously there's a huge difference in GRT output between 22in and 26in so need to get that right.

Also trying to make GRT output fit (as much as possible) some measured velocities on a new load, by adjusting 'initial pressure' and it gets very close is when 'initial pressure' is set to zero. Instructions say that 'initial pressure' is there to be used as an adjustment for this purpose - is setting this value to zero reasonable as long as it calibrates GRT with real world velocity results?

Any advice appreciated, cheers.