i have seen the butt hoocks that go under your arm. has anyone seen or tried to reverse it so that the rifle almost sits on your shoulder???
it makes sense that if the rifle is hanging on your shaoulder that it could be better????
If by this if you mean with the 'hook' section going over the top of your shoulder, the only time I have seen this used is where the shooter is using a bullpupped GC2 rifle. The balance on this rifle is very much to the rear, so setting the butt hook this way may have some benefit.
On a conventional rifle with a balance point further forwards, I wouldn't think such an arrangement would be too good.
As to legality, I don't see why it should fall foul of the rules, your current 2007 rules, specifically Rule 1 regarding rifles does not say that such an arrangement would be disallowed.