Very nice work....on all of it. You definitely have more skill than I. Wish I had more time to complete some of my wanted projects.
Speaking specifically of the holster, the most important question is...."How does it feel?" The cosmetics (and they look great by the way) will change with practice, wants, desired look, etc. But the trick is to keep the gun secure, with little to no discomfort.
For retention (on a pistol), I usually bone the ejection port recess and indent inside the trigger guard. When working around the trigger, make sure the gun (or mold) you are using has the trigger in full out position. Some guns, like Glock (and likely your SR40), will have the trigger out when striker is set (cocked), but stay in a rearward position when fired without ammo. You don't want to work the leather with the trigger back, then have a fully loaded and cocked firearm pressed into a holster only to have the leather push the trigger back. Ouch, could be a good case of Glock-Leg.
Long shot I know, but I wouldn't want to even partially be responsible for an "unfortunate" chain of events.
My little trick for the trigger guard recess is to use a small bouncy ball. I make sure the trigger is full forward, then place a little rubber ball over the area and clamp. I use the "Quick Grip" style of bar clamps for most of my wet molding tasks. In fact, I usually do most of my wet molding at a single time. While the gun (with rubber ball) is clamped to a small plastic board, I'll do the rest of the tight area boning at that time. That way I don't have to wait and rewet the leather all over again.
For the comfort aspect, my trial and errors have brought me to the fact that I don't want any "hot spots" or pressure points on my body. Not always easy to do with a 3-D object and protrusions such as safety levers and such. I wear a firearm 7 days per week, so comfort is always an issue. So my own holsters are now done with the full firearm molded into only the front leather slab. The back is sometimes reinforced, and as flat as possible. This allows the back to mold to my body over time. And as the front leather is the only source of gun shape and retention, if it relaxes a bit over time, the back portion actually creates a few new points as it curves in and shapes to the body.
My favorite stamp is exactly what you used, a basic basket weave. With a nice deep stamp in well cased leather, a full coverage design like you used actually increases the leather rigidity and ability to hold the gun shape securely for a long time. I don't remember exactly when I put my current holster into service, but it's going on two years, at least. And still has nice firearm retention, even after many hundreds of gun draws and reholsters. No, not from gun fights,
, but from many potty breaks and changes of clothes over the last couple years. Mine shows some wear on on the top edges from many lazy reholsters.
I also started lining the back slabs only. Partially for looks just to cover up the flesh side of body shield, and partially for rigidity. The thin embossed lambskin that I have been using doesn't add the strength, but it's the function of bonding the two with contact cement that does it.
Just for fun, here's some old recycled pics. The first is my daily wear rig, pic taken about a year ago. The next two are of a holster I made nearly a year ago for a friend and his SR9.
