Nicolas, I am not a ‘carbine’ guy but it would help us if you told us your ultimate goal – do you want a shooter or a wall-hanger? Is the barrel you have new or an original? Why have you decided to start with only an action and not with a more complete specimen that could offer a chance at some parts that at least fit well from the start? I assemble Krags from bunches of parts I have amassed and, at times, I find I have to shift my parts between rifles to get the best fit – stocks included. If you seek a shooter, regardless of the barrel used, a reproduction stock can be custom fitted and even glass-bedded to tighten things up. Beautiful and good shooting rifles I seek to make but I by no means attempt to clone an all-original Krag. I do like my cartouches matching the year of manufacture though! I also prefer a salvaged original ‘junk’ part over a reproduction piece. With a little more information from you, the carbine guys on this forum can probably get you headed in the right direction. Good luck with your project!