I lost quite a bit of accuracy on a Rem 700 in 300 Win Mag and found that where the 180 grain Accubonds used to be seated .020 are now .042 . This is with the same lot of bullets and were measured last summer with a Hornady LNL. I also have an old half used box of Sierra 180's from when the gun was new that the bullet seating depth has increased a total of .032. I am sure this is due to errosion and I will try a new seating depth but my question is how detrimental is this? Do I need a new barrel? How much overall erosion do you allow before rebarreling?