Another thread about prone

So after scrolling back through the pages of threads in the basic marksmanship section I have learnt ALOT about what to do and look for in a good prone position.

So my question is about shoulders, now I know that the left shoulder/elbow position can affect group size vertically and the right one can affect group size horizontally.

So when I get behind my rifle I set my self up and make sure my elbows are in line and shoulders square, but after videoing myself (weird I know) I have found that my left shoulder is higher then my right (note, right hand shooter). When I line up my elbows, my right shoulder is lower because it is behind the butt and my left is higher because my elbow is supporting my body, I know that the skeleton is supposed to be the supporting system apposed to the muscles.

So should my shoulders be level (not inline, I mean like if I put a bubble level behind my neck) and should me left elbow be directly in line with my right one or in towards my body more to give better support?

Thanks in advance guys,
 
Thanks for the reply. I always make sure everything is square with the target, before I shoot (Thanks to all the threads on here about that) I never used to shoot with the butt in the 'pocket' of my shoulder, I thought my collar bone was more comfortable but now I have adjusted and have the top of the butt in the pocket.

I will try lifting the stock on a higher bag, I use a 9-13 bipod for all my shooting, I find the 6-9 to be too small. I will keep working on my position. I think I have improved 100% from what it was.

After studying the day one DVD I have been setting up the NPOA first then standing up and positioning my body to the rifle, the only thing I have found is what I said before, that my shoulders arnt the same height