Dale: I haven't bought the materials for a rifle from the folks you'r talking about but I will make some comments about pre inleted stocks I have bought.
When they say the barrel, trigger, lock etc are pre inlet, it doesn't mean the parts actually fit.
All of the parts will require some hand fitting.
This often means removing just a little wood here, and a little wood there. It sometimes means removing some metal. It all depends on who is providing the pre inletting.
The method of removing the wood can be with a very sharp Exacto type knife or with a small file or with sandpaper. (Glueing a small piece of sandpaper to a piece of wood works pretty good.)
Whatever you do, avoid using power tools like Dremel high speed grinders. They can ruin the stock faster than the blink of an eye. The "One second it was good, the next second it was gone!" sort of thing.
Leaving this extra material by the supplier is actually for the best. I say this because all of the parts have tolerance, that is to say, they are not exactly the same. In order to have the parts fit exactly into the stock, the only way to do the final fitting by hand.
I don't mean to scare you off, but I also don't want you to think the parts will just fall in place. If you did, you would probably feel like you got the short end of things, when actually you got just what you need.
If you have any questions about what to do after you get your parts, just post them here and you will get more guidance than you can stand. :: ::