I believe I have experienced my rifles placing bullets differently depending upon how the rifle is supported. Additionally, I have read various others saying that shooting from a very hard support will make a rifle shoot high and they advise using a buffer, such as a rolled up soft jacket, between the hard support and the rifle.
I zeroed my two .30-06 rifles from a firm support comprising a small sandbag filled with lead shot sitting on top of a metal shooting platform. I then began shooting both rifles from a sitting position, resting my elbows on the middle of my thighs. The bullets from both rifles went to a substantially different point on the target, about 2" to 3" low. Additionally, I have also found that shooting from fiberglass wands that my bullets shoot substantially higher, maybe 3" to 4" higher.
What has been your experience? I'm bringing this up because I don't understand why this should be the case. Also, I do not like this and would prefer that I discover there is some fault in my shooting technique rather than that the rifle responds differently to different support means.