Wow, why do so many of you guys think a velocity window is where a bullet is most accurate?
A bullet will be accurate in many different velocity windows, this is why once you determine best seating depth at a moderate velocity window, which is coarse seating depth testing, that it will hold true throughout the rest of the testing.
Primer, powder and seating depth testing done initially are coarse testing.
Fine testing is primer seating depth and powder variation.
It is very rare that a seating depth needs changing after initial testing finding the best depth.
If you use a tuner, then this fine testing may not be necessary at all.
It's funny, I see Eric Cortina, Ryan Furman and others all shooting with their Labrador's set up every session.
I do all my testing without a chrono, only once I have found best seating depth, best primer and primer crush, best powder do I get my 2 chrono's out and start seeing what numbers I get. I already know what pressures I'm running, the Pressure Trace is invaluable for my testing, even without knowing the velocity…
My 6.5x47 Lapua is the easiest tuning cartridge I have ever used, even easier than the 6.5x55 Swede. I can almost use any correct burn rate powder, primer and bullet and tune it just with the tuner, don't even need to do a seating depth test, just jam and go.
Sometimes, we look into stuff too much and just make it more complex that it needs to be. I am guilty of this too.
My 338-416 Rigby Improved is a perfect example, I made it more complex than it needed to be by concerning myself with CBTO and building the rifle, chamber and brass to suit this parameter, I should have just built the rifle, then cut the chamber and whatever the CBTO was going to be with the bullet, as it is a single shot anyway and the rifles magazine is moot in this application, and just let it be what it was going to be. Now I am restricted on OAL by the throat that I cut, which is now at it's end of life and I can't setback and recut the chamber because of my design choices.
At 900+ rounds, it is very tired and doesn't produce the desired precision anymore.
It's still accurate, but has more fliers and will not respond to fine seating tuning, so it's done in my eyes.
Had fun with it, it turned my hair greyer, and gave a learning curve that I now use on all my precision rifles, whether that is for comp or hunting makes no difference, same testing for either.
Cheers.
