I just picked up a XD45c with the 4" barrel for CC.  I am having a hard time finding holsters for it.  My question is, are the 9/40 guns the same width as the 45?  Will a holster for a 4" 9/40 work in my 4" XD45?  Thanks for your help.

I just ordered an XD .45acp Compact for CCW. For carrying it, I ordered a Don Hume Model H721OT for mine from "XDpistols.com:

XDpistols.com

I also like Kydex paddle rigs. G-Code makes a nice one. I am thinking on getting this set up from Gunners Alley:

Gunners Alley/G-Code Holsters

I am not sure of the frame and slide dimensions of the .45 vs. the .40/.9mm......maybe someone on the XD Forums will know:

XD Talk Forums

When the XD45 first came out, no one was making holsters for it yet, so I ordered a FIST holster made for an XD40. It fit just fine.  Also, take a look at the Crossbreed holsters. Money-back, 2week trial and it's one of the most comfortable holsters for the XD I've found. http://www.crossbreedholsters.com  I carry my XD45CT in a QwikClip Crossbreed

http://www.blade-tech.com/

I CCW my XD45 comp daily (when in America). I use a Crossbeed supertuck. I bought it a few years back and have since bought the quickclips, but still keep using the the Jhooks. Thinking about picking up a mag holster from him soon. I have used my Crossbreed holster to carry my XD40 SC on a few occasions as well. No issues were noticed and it retained it just well. When I got my first XDm I put it in just for thought. It fit and was held fine.

For a OWB holster, I have both bladetechs and a blackhawk serpa. The bladetech is a light bearing since BH did not make one. Its great. The Serpa fits all 6 of my Xds, (45, 40, and 9) SC thru tactcial and the XDms.

Well the general consensus seems to be that any XD holster for a 4" gun should work.  Thanks.

Get a Comp-Tac MTAC.

http://www.comp-tac.com/product_info.php?products_id=95

I use one to carry my fullsize XD, and I used to use it to carry my 1911 before that, I just bought the new body and swapped them.

The compact XD45 shouldnt be any different from the fullsize since they both have the same 4in barrel.

That being said I got my holster with the  XD "slide" body incase I later end up getting a XD Tactical, and it should also work with any of the other XD pistols except the XDMs.