I used to CCW a 4506 when I was in law enforcement; in colder months I used a Galco Miami Classic shoulder holster, in warmer weather I used a Bianchi belt slide holster under a sport shirt...but that was back in the '80s when holster choices weren't as plentiful as they are now...
IWB-I use an El Paso leather holster that I picked up used. The previous owner said it fit a Beretta. Well, maybe it did but it fits all of my large and medium frame autoloaders 4506, 1076, 645, 5906, 4046, 4586
OWB-Galco B719 T. It is a belt slide and fits all of the above pistols and even my Sigma works in it, but not as well.