Your money invested into an aftermarket receiver should mean it is assembly ready. Your "gun plumber" of choice should have literally nothing to do other than stab a barrel and fit it to the stock. For years there's been this mythical idea that somewhere deep lies some sort of hocus pocus whatever that means the difference between shooting in the teens or minute of bill board sign. Here's the secret: Buy good parts and have the fit up done by a reputable shop. It's really that simple. Gun work at its core is very much fundamental machine work. Round, square, parallel, concentric, and good surface finish. Stick to that and 90% of this is licked. Complex organic shapes that require the latest in sophistication just aren't present in this industry.
The actions made today do a good job of adhering to those principles. Actions that are exceptional in today's world are a relatively small crowd. These are the folks who've gone a step further to improve the interface with the user. Better PE, better geometry with the bolt, more robust extraction, material selection, coatings, etc. The thing to take from this is, if you get to go shooting and all your doing is shooting...then you got a good piece. Look left, look right. The guys with a black cloud of expletives following them around are the ones who didn't fair as well.