Yes the reciever can be threaded, I think the bore dia. is .687 which is the correct size for a 3/4 - 16 thread. Of course when you do that you have to make a new barrel and cut the extracter slots. When you do all of this you really should face the bolt to set the recess in the bolt face at .0425 to .0435for minimum head space. You can also square the bolt so that the two pieces line up striaght.
This can go on and on, that's why I have four of then never ending amount of fun. I've restocked then, rebarreled them, worked on the triggers, there is always something to work on.
Just put a Green Mountain Octagonal barrel on one, refinished the stock, added an ebony forearm tip, looks great don't know how it shoots, Okla. had snow and temps in the low teens and I aint tuff enouhg to shoot in this kind of weather.
