Originally Posted By SteelonSteel:
go through some of these links here;
they're from the us army marksmanship unit and are posted on the CMP website and I'm sure on theirs as well.
lots of other essays on different aspects of the sport there too.
For prone with the .30 cals if you're postion is getting knocked around by recoil I suggest trying to use the open leg position. The bent leg I like better for the AR's though, the little recoil doesn't do bupkis to that position. Of course, thy them both and see what you like and what works better for you. There are common position methods that work better for "most" shooters but in the end everyone has to make some adjustments for body type, arm lengths, etc. We're not cookie cutter people.
The right leg bent forward and your body rolled onto the left side works well for me IF your body is directly behind the rifle, not angled out to the side. As long as you weigh over 80 pounds, the recoil won't knock you around while shooting any .30 Cal rifle. I started this when shooting Infantry Trophy Matches and enjoyed it so much that I use it for slow/rapid prone also.