Don't we have a search function on the forums anymore? There are many many threads on this and the same"stuff" is posted every time.
here's something a little different...
I've been documenting my break in testing with pictures on another forum.
In short, i postulate that a short break in process is conducive to low SDs by eliminating copper fouling as a variable. (i make no claims regarding accuracy, though tighter velocity spreads obviously affect vertical dispersion at longer ranges)
On one barrel, i document the break in, then clean again at various intervals, after 25 rounds, up to a couple hundred, to demonstrate that copper does not build up meaningfully after break in.
On the other barrel, I document the break in (2 rounds), then chrono at various points and am over 500 rounds.
At 182 rounds, (180 rounds since it was cleaned) I chrono'd and got
2779
2779
2783
2782
2779
which is a 4 FPS ES and a 1 SD.
At 390-400 rounds, I chrono'd 10 rounds and got an ES of 11 and SD of 3 FPS. The point being, the barrel hasn't been cleaned since the 2nd round. So, 398 rounds since it was cleaned, and it's still shooting reasonably low ES. AND, once the velocity stabilized, from 182 to 400 rounds, the Mean has only moved 2 FPS.
I'm sure lots of people get low SDs on this site too. My experience is that when i don't do a break in, I have to clean more often and I can get 1 SDs but not for very long. Usually only from 5 to 20 rounds or so after I clean, then my SDs go up to 7-10 FPS. But without copper in the barrel, I can go hundreds of rounds and still get very stable results. I get the same accuracy at 100 yards either way.
you can read the thread here
http://www.thehighroad.org/showthread.php?t=797080.
I'd be curious to hear if anyone else sees similar results on the chronograph.
edit: 4 days ago, btw at 515 rnds, i screwed it up and had to foul back in for a few rounds, but the last 4 rounds over the chrono were
2783
2783
2782
2777
then yesterday i went and chrono'd 2 rounds just to check before i drive to the Accuracy International Long Range Classic in FL today and the results were
2782
2779
so from round 182 to 535, my average velocity has changed less than 2 FPS