I have tried a few OWB set ups while wearing a loose fitting T-Shirt, but my T shirt tended to bunch up on top of the gun. I bought an IWB leather holster for my small revolver and can't quite get cozy with it. Your comment about the belt makes a lot of sense, and I suspect my belts aren't wide and supportive enough. I wish I had a good shop around here. The one shop that has the best and equipment has ridiculous prices and the workers are kinda dicks.
