Posted by Anthony Hall on Jan 12, 2012; 5:20am
URL: http://oldforum.flyshooter.com.au/6BR-throat-errosion-question-tp5136769p5139030.html

Hi Dennis,

I would think Pete is exactly on the money with his response.... what you may be experiencing is something that I found.

I believe that most loads work either best jammed or jumped, but when you get too fine with either they open up.  If you started with 0.005" jammed and the lands moved 0.007 there is a period where some are jumped and some are touching etc...

In my opinion, you need 0.010" + either jumped or jammed to allow slight variations in seating depth and or even carbon on the lands between cleans etc not to affect the pressure and therefore velocity etc.

Obviously with Petes example of not changing a thing for 2000 rounds, there is only a short period where tolerances are close while it transitions from jammed to jumped.

Cheers

Anthony