rklaver,
Welcome to MarlinOwners.com.........
RE: your question.........What papabear said is true.............
First, I wonder how you were able to buy only a receiver. I would expect the fact that you could, may mean that receiver already has some dimensional issues.......Barrels are much easier to get........What caliber receiver is it? do you actually know?..........I will tell you that while the different calibers look to be the same......dimensionally they are NOT........some have added functional cuts/operations added to facilitate a particular caliber.
Speaking as a Manufacturing Engineer, RETIRED from Marlin Firearms Co. at the time of the closure of the North Haven facility, I have something to offer..........
All major components continually went thru small dimensional tweaks for a number of reasons, and still do today..........
I know,.....you would think that a product that has been in production so long, would have all the bugs out.................
NOT SO............A small tweak in one area, means a small tweak in another.....
Or, a particular operation gets changed to make it easier and faster to perform, or because the change will yeild more parts with less scrap..........
Or, Marlin Gunsmiths ask for a change to make their job easier and faster.........the list of reasons goes on and on..............
Most times, these changes can be "retro fitted" or "fitted forward" with a little work and understanding..........sometimes not..........
Is it possible to you to build a Marlin from parts?..............sure, if you can get the right sequence and caliber of parts.........
If you don't, or can't, then the results will be clunky, nonfunctional, unreliable and even dangerous............
You will find some parts will be available ONLY to gunsmiths with FFL's, and other parts will be "Factory Install Only" items...........
As Jack stated above, Its cheaper faster and more reliable to start your custom rifle with a complete donor rifle...........
Tom