Finally got out to the range yesterday afternoon and ran a box of Hornady 168gr AMAX through the Eddystone. Setup on a SR1 target at 100 yds & two sets of 10 shots yielded 96-3x & 95-2x . Was shooting prone off a sandbag with mild but gusty crosswind. Checked muzzle pressure before and after each 10 round set using a Lyman trigger pull meter and noted that the muzzle bearing pressure decreased after each set of shots (went from 2 to less than 1lb). So something is changing the muzzle pressure as the barrel & breech heat during firing. Action screws did not move and were torqued before shooting. Plan to disassemble the rifle and check again for clearances in the barrel channel or evidence of rubs.