That's what I try to do - build practice ammo that shoots like the factory ammo I carry for self-defense. However, (don't take this the wrong way - I know what you meant) you're going to have a hard time "copying" factory ammo "recipes." About the closest you can come to "copying" factory ammo is using the same bullet weight and type, and
possibly brand, and kick it out at approximately the same speed. You're probably never going to find out what kind of powder the "factory" used, much less buy any of it for yourself.
But like I said - I know what you meant. I do the same thing.
BTW, my wife and I completed the Idaho Enhanced Concealed Carry Course last summer, and the Instructor, a County Sheriff's Deputy told us that it "wasn't a good idea" to carry handloads in our carry guns. Now I don't know if he was right or not, and I will
not argue about it (everyone can do what they want - it's no skin off my nose) but neither my wife nor I have ever carried anything other than factory ammo in our carry guns - not even before we took the class.