When I bought a galco years back they had instructions that came with it. It said to rub and massage the holster all over like a ball glove, and that the gun it was made for would not go all the way in until this was done. I followed the instrutions and just massaged it hard with my thumbs and fingers for a couple hours while watching tv...not bending it, just moving it, massaging it...after a while I could get the gun all the way in, leave it in there for a day or so, and then weant back to working the leather all over again...in time the gun fit like a glove. But it was lot of work and your hands get tired. I now do this with all new leather holsters that are real tight when new, don't know if Galco puts these instructions on holsters anymore....but the one I bought warned not to try to shove the gun in there first thing, and also said it was real likely you would not be able to.
The methods above are real good methods to, probably less work to.