ORIGINAL: Arthur P
I would have thought that at 40 yards the feathers would have impacted much much LOWER than the blazers... usually they are dead even to 30 yards but past that feathers start slowing down a lot quicker than anything else.
That's totally incorrect. Urban myth perpetuated on the internet. Feathers and vanes will shoot very close to the same POI out to at least 80 yards. No sweat. I shot field archery competition for years using feathers for dry weather and vanes in damp weather, with no need for any corrections whatsoever. I'm far from the only one to do the same, with the same results.
I can only guess that your bow tune was never quite right in the first place, WBowhunt. Probably, as Swamp Collie said, you were getting vane contact some how or other.
Dang arthur.... I look up to your tech skills... but mine are WAY different. Now, I tend to put a fair piece of helical on mine (feathers)... would that make the difference compared to a straight offset blazer? Mine at 40 are like 4-5" different.