I am having a ton of trouble with this too.
I try my CZ75 with it's Bianchi OWB holster, and it just doesnt work. I wear it with a really thick, really stiff Ariat belt.
When I wear it, it is totaly obvious. It sticks out in the side, and when I lean over it pitches a huge tent in my back.
When my buddy puts on the same rig with a similar shirt, it dissapears. The gun is tucked right in against his side and stays there, and moves with him when he leans over.
He takes it off, I put it back on in the same place, and I have the same problems!
And we are of similar size and shape. It doesnt make any sense, and it is really frustrating.
Any suggestions?