If you try to do the spring without the "special tool", be very careful. That damn thing bites and its fast too!!!!
I've built 2 FAL's and they are great "battle rifles". Lots of meat!!!
But, like an AR, they get boring when you get down to the "assembly" part of the build. Just plain ole common sense!
Slso, they will get your attention when you pay to feed those things. 308 is getting mighty expensive!
When setting your headspace make sure to remove the extractor from the bolt. Then find the pin size that you can close the bolt on with light "two finger" pressure. Take that pin size subtract .002" to get to nominal headspace, then add .001" for setback and you will have the size for the locking shoulder you need.
there are a couple of tutorials on falfiles.com