First, an apology if this is posted in the wrong area or if someone has already answered this, I did do a quick search on "rollover" yet came up with nothing. I am kind of new to forums and am not all that up-to-speed on finding what I am looking for, so if I missed the answer, sorry, provide the link and I will follow...
First the story/facts, then a question below:
Many months ago, after zeroing for point of aim/point of impact at 100, I began a rollover prone 10-shot group experiment at 100 yards. The intent was to keep the same point of aim of the shot group that was center mass for both the left and right rollover prone in order to show the impact difference when rolled over to the right and left were applied.
When shooting with the ejection port side down, I got the expected grouping (low and right).
However when shooting rollover prone left - ejection port up - I was shooting high and left (almost as high left as I was low right).
Being puzzled and wondering about counter-intuitive results, I then repeated experiment, except this time I supported the rifle by sandbagging to help take out any human error/input. Yet, I got the same results, albeit with tighter grouping.
The left, ejection port up, results made no sense to me... I kind of mulled it over, and I guess I filed it in the "talk about it later" category of my mind.
Then a couple months ago I was attending training in Louisiana at the state police facility, and while I was shooting I had an instructor join me on the line. I watched as he ran his own test on the roll over prone (strangely enough he was conducting the same experiment for the same reasons). I was very curious to see the results he would get, especially on the left side. However I kept my mouth shut and didn't tell him my results because I didn't want to "poison the well."
I respect this guy, he is a good shooter, and he was shooting with with a free-floating barrel, something I did not have in the original experiment. When we went down range I could see that his grouping was almost identical to mine, I watched his face as he examined his target and realized the look he had on his face must have been the same as mine when I shot the experiment. Next, as I went back to 100 to shoot more, I saw him set up sandbags and shoot the same test, now supported (smart guy). Now it was no shocker to me that he came up with the same results but with tighter groups. At that juncture I explained to him my results of months earlier were identical to his. We were both stumped.
I brought up the subject to some fellow instructors and teammates here in Iraq (all, snipers, competition shooters, IPSC, etc..., most - if not all all - with combat trigger time), yet no one can seem to figure out what was going on.
I have asked a fellow instructor to shoot the experiment without sharing the results of my experiments with him, and hope to hear back from him soon.
I am baffled, this makes no sense to me. I have to think that there is something we are missing in this equation.
My initial assumption is that there is some shooter input (shooter error) that we are not accounting for. No one is perfect, I am not, but I am an accomplished shooter, as was the instructor in Louisiana... so I am still stumped, as are all the quality shooters I am around.
Now the question:
Has anyone else experienced this themselves, or seen it in students? If so, what's going on with the left side prone that I am not understanding or missing? What was the input (shooter error) that caused this, and did you do to correct it? Or is there some exterior ballistic magic that I have never heard of before going on here?
Let me be perfectly clear, I am not asking for theory alone. I am asking for someone who has seen the same phenomena (either in himself or his student), figured it out, and has an real tested and proven solution that I can try out as soon as I get back to the range.
Preferably someone who has photo or video documentation of the problem and solution set... and crayons, I need lost of crayons with a coloring book because I am a visual learner. (Okay, just joking about the crayons, but all the documentation you can give would be much appreciated.)
Thanks in advance for your time,