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ES 3-6 is possible, but extremely difficult, and probably not repeatable for four 5-shot groups in a row without extreme procedures and an exceptional barrel. The best F-Class shooters I know are achieving 10 or under ES for five shots, pretty regularly. This is with regular annealing, AutoTricklers, base-to-ogive sorted bullets, turned necks.
ES does not directly correlate to group size on target. However, consistently low ES is a darn good indicator that you are doing things RIGHT during the reloading process. This would include:
Very consistent powder charge
Bullet base to ogive held very consistent
Neck tension consistent, and neck chamfers smooth and consistent
Consistent seating pressure (now measurable with AMP press)
Good selection of primer for your powder and primer hole size
100-200 is a different game. No question some insanely good groups have been shot with high ES. However I have every confidence that ES over 20 will show up at 600 yards on target as a lower score and bigger group size. My 6BR loads for 600 ran around 11-12 fps ES. That was with Varget and CCI 450s and Scenar 105s.
Back to the OP -- If he wants to get the ES below 20 fps he needs to consider changing powder. But the issue is probably related to the barrel.
I wasted nearly two years trying to get a factory .260 Rem barrel to shoot. I finally replaced it with a 6mmBR PacNor. The first measured group out of that barrel, rounds 17-20 (4 shots), was a witnessed 0.168" at 100 yards. ES about 15-16 fps, if I recall. Switching to an arbor press and getting more carbon inside the necks lowered that to 11-12 fps and I was happy with that, as the gun had less than 2" of vertical at 600 yards (with low winds).
The eye-opening discovery of going from a 0.8-MOA .260 Rem with 20+ ES to a quarter-MOA 6BR with ES in low teens (with exact same action, stock, and trigger) was what inspired me to start this website way back in 2004, as 6mmBR.com .
ES does not directly correlate to group size on target. However, consistently low ES is a darn good indicator that you are doing things RIGHT during the reloading process. This would include:
Very consistent powder charge
Bullet base to ogive held very consistent
Neck tension consistent, and neck chamfers smooth and consistent
Consistent seating pressure (now measurable with AMP press)
Good selection of primer for your powder and primer hole size
100-200 is a different game. No question some insanely good groups have been shot with high ES. However I have every confidence that ES over 20 will show up at 600 yards on target as a lower score and bigger group size. My 6BR loads for 600 ran around 11-12 fps ES. That was with Varget and CCI 450s and Scenar 105s.
Back to the OP -- If he wants to get the ES below 20 fps he needs to consider changing powder. But the issue is probably related to the barrel.
I wasted nearly two years trying to get a factory .260 Rem barrel to shoot. I finally replaced it with a 6mmBR PacNor. The first measured group out of that barrel, rounds 17-20 (4 shots), was a witnessed 0.168" at 100 yards. ES about 15-16 fps, if I recall. Switching to an arbor press and getting more carbon inside the necks lowered that to 11-12 fps and I was happy with that, as the gun had less than 2" of vertical at 600 yards (with low winds).
The eye-opening discovery of going from a 0.8-MOA .260 Rem with 20+ ES to a quarter-MOA 6BR with ES in low teens (with exact same action, stock, and trigger) was what inspired me to start this website way back in 2004, as 6mmBR.com .
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