A couple come to mind to tote a 4" N OWB somewhat discretely. A Simply Rugged Sourdough Pancake looks bulky (it's not), however when worn with a pistol it "simply" works. Belt slots are cut to balance gun weight well, and pull gun butt nicely into the body. Top of the holster leather protects the hammer and sights and keep both away from wearer and ones clothing. Grip is well exposed for a smooth, quick gun presentation. Gun, including sights, is well protected from dings of daily life.
Another option, if you want to be a little retro, is an original Roy Baker Pancake holster. Yes, it does expose the trigger, which is not "modern". Should do fine in concealed carry mode.