I've got a repro GI sholder/Chest holster, the type witn a single strap that you simply duck into. It is not a concealment rig, as the strap circles the neck and shoulders and is visible from the front. Look at about any WWII Pacific Theatre aviator and you'll see one.
It can carry my 4-5/8" Blackhawk, my M28, or my Hi-Power (not intended, but you can wedge it). Keeps the pistol clean and dry, away from other gear or a pack belly band. You can draw from seated/and buckled in a vehicle or on an ATV without a hassle. And you don't need a belt to use it. Hang it on your bedpost or tent pole, slip it on in your BVD's right out of the sack.