Hello, everyone.  Last weekend, I was finally able to get out to range with the British Proofed Remington rolling block Mid-range .40-70. firing line is covered, temp. was in mid 80's.  I noticed while peering thru tang sight appature, the hole appeared to be changing shape..the target bull still appeared black & round..but it was as though a drop of oil was obstructing one side of appature.  Then I noticed I was getting two distinct grouping on target..not from consecutive shots..right above one another..one in center of bull, the other at top edge of 6" black bull..windage identical for both groupings.
  Wonder if heat off brl.?  I was shooting 70gr. Swiss 1 1/2 & noticed brl. getting quite warm..or maybe my 50 plus year old eyes were playing tricks?
    One thing that couldn't have helped..I had forgotten my shoulder pad..and that 10lb. regulation match rifle was sure backing off that 330gr. Brooks Creedmoor bullet!  My shoulder has some nice looking "case-colors"!