I just picked up one of these. It is all matching parts and has good rifling but has been reblued. As far as I can tell it is WWI production (sn in the 300,000 range). My question is does anyone know the legalities regarding the shoulder stocks. I don't want to register the weapon just to be able to put a stock on it but since it is cut for one it would be neat if I could put a stock on. Anyone know if there is any sort of grandfather clause that covers this or do I have to register it as a short barrelled rifle to add the stock?
Jason

As much as I hate to say this, I really think you will have to call thr ATF for a ruling. To the best of my knowledge, you can't put a butt-stock on any gun with less than a 16" barrel. They put this in the same class as a sawed off shotgun, and a machine gun. If the piece qualifies as an antique or a curio the rules may be different. I think you would have to go straight to the horse's mouth for the correct answer. If they tell you "YES", get it in writing.
Another example of your tax dollars at work.