Thank you for all the info.
On my 550b I have, and on the 1050 I had, always used that return spring feature. I sold my 1050 to a friend once I got my Mark 7 working consistently.
Currently I'm loading this on my automated Mark 7 Evolution. The powder drop consistency with their upgraded system is excellent. Using the GemPro scale, which is more accurate than I need, down to +/- 0.02 grains, my variation of N320 is always within 0.08 grains and and usually 0.04 grains.
I am using a LabRadar for chronographing my rounds. It's a Doppler based system. I use it mostly indoors now at my local indoor range where I have a cheap membership, since it's 110 degrees. This works indoors or out, day or night. From what I've heard and read, accuracy for these is as good as regular chronos. I've tested it side by side with two other conventional chronos and the velocities have been within 10 fps of each other for any given round.
I just realized that all my barrels are probably getting up there in round count. The accuracy remains excellent with all tested barrels, and I've traditionally used that as my trigger for buying a new barrel. But....could that be one possible cause for the ES and SD variations despite retained high accuracy?
Now, this issue is to me as much a fun experiment as it is a practical issue for passing chrono at the next match.
