http://www.sideguardholsters.com/ I personally have a Sideguard "The Slide" OWB holster for my P-11. It has an open end, and would work excellent for the P-40 as well. Sideguard holsters are VERY well made, my P-11 with loaded magazine (empty chamber obviously) can be shaken up and down and the gun will not fall out. I also like that all their holsters offer full slide protection from your body, helps keep corrosion at bay a little more, as does the use of CorrosionX gun oil (which is ALL I use on smokeless guns).
There are a Lot of choices out there, but I am thinking of getting a holster from Sideguard for my 1911 soon. I am a very happy customer!