Ruger GP100 Concealed Carry in California
Here in sunny Southern California, a law-abiding firearms owner is allowed to concealed-carry only on his own property, or at his "temporary campsite." To and from the campsite, or for that matter to and from the home (to the range, gunsmith, etc.) the gun must be transported in a locked case with all ammo in a separate locked box. That is the law for all of us who do not have a CCW permit.
All that to say that I do not usually venture out into the real world with a gun under my belt. However, in the backyard, on the porch, around the campfire, in the tent... I have used a Bianchi 6D ATB Waistband -- size 4, which is a soft suede IWB holster with thumb-break hammer strap. This holster was less than 30 bucks at a local Turner's Outdoorsman, and it fits my 4" GP100 very well. The snap for the thumb-break is made of heavy-duty metal and has a nice plastic (non-scratching) coating on it. The hammer strap is adjustable, using a velcro system. The clip that holds the thing to your belt is made of a high-quality spring steel that really grabs well, and gives a very positive draw. This is a well-made soft-sided holster and a very good value for the money.
I see on the web that Bianchi makes the same holster in "size 3," but I'm not sure if the girth stays the same as the 4, with simply a shorter length. Worst case scenario, I would think a size 4 could be cut down, if a GP100 didn't fit in the 3. Or the extra length could simply by let to flatten out inside your pants (to hang down).
While this holster is also available in a left-hand version, I have the RH (right-handed) model, which goes clip-facing-out IWB on my right hip. The gun is drawn with my right hand. The holster could conceivably be worn on the left hip (gun butt forward) if a right-handed person wanted the crossdraw that WESHOOT2 suggested earlier in this thread. I have also, from time to time, clipped the holster inside the front of my pants, "badass style," so that the barrel hangs down just to the right side of my manly package. Using this technique, the gun fits smartly between my upper inner thigh and my "middle leg." Also, my large beer gut seems to hang over and help hide the GP100's rubber monogrip. However, I find it hard to sit down with this configuration. I have to lay back almost horizontal in any chair I attempt to plop down into, and it makes me look like some kind of a slacker. If the gun "prints" while trying to sit in this leaned-back position, I am instantly classified by all present as a badass gun-toting maniac type of person. Also, the barrel, pointing at my junk, gives me an uneasy feeling that I cannot seem to get past, the feeling that at any second I may become intimately familiar with point-blank hollow-point ballistics. For these reasons, I typically carry the gun out on my side, still inside the waistband, but directly beneath my right-side pants pocket.
Hope this helps.
---BST