a lot of the newer takedowns are made so that the bolt lugs lock into the barrel rather than the receiver. there is less wear that way & they are supposed to return to zero better. instead of the front of the receiver being threaded its reamed straight back past the bolt lugs. the barrel shank is turned to about .001 under the diameter the receiver was reamed. to take the rifle down all you do is remove the bolt & pull the forearm release then slide the barrel & forearm forward out of the receiver.
the older style threaded takedowns were done a couple different ways & actions that have course or square threads like mausers & springfields seem to wear better than actions with finer threads like remington & winchesters. full thread takedowns also wear better than interrupted thread takedowns. on a interrupted thread takedown three equally spaced sections of threads are broached out of the receiver & barrel so you only have to rotate the barrel 1/3rd of to turn to release it. the interrupted thread takedown is good if your to lazy to spin the barrel a few turns or your to cheap to buy a nice set of talley Q/D rings for your takedown rifle to keep the scope from hitting the forearm & stopping you from being able to unscrew the barrel from the receiver.
there are a couple different ways to attach the forearm & latch to the barrel. i think the best way is to use a sleeved rear sight base to attach the forearm & latch.
using a soldered on sleeve also lets you easily adjust for wear in the future if you also use a banded front sight & barrel band sling swivel. with no sights its even easier because you wouldn't have to line the front sight & swivel base up.
some builders just cut two dovetails in the bottom of the barrel for two winchester 70 style forerarm hold downs & inlet the latch to the forearm.
most takedowns use 1/8" steel plates where the stock & forearm meet.
the plates are usually screwed to the stock & forearm but sometimes they are also tied into the bottom metal & latch assembly.
the latch is usually a shotgun style lever that attaches to the steel plate in the forearm or attaches to the bottom of the sleeve that holds the forearm on. some of the levers are hooked to a rod that slides through a hole in both plates locking everything together. some builders make the end of the lever with a hook shape that goes through a rectangular hole in the forearm plate & hooks into a corresponding rectangular hole in the receiver plate camming the stock & forearm together making them as solid as a 1pc stock.
i have a takedown project rifle i'm slowly piecing together. its being built as a takedown version of the mauser model c. i still need to order the barrel & scrounge a couple of other parts. the plate has been fitted to the buttstock, i cant fit the plate to the forearm untill i get the barrel & rear sight sleeve.
i'm going to slightly extend the front of the bottom metal so it butts up to the plate then tie them both together with a countersunk machine screw.
