Raimey,
I haven't responded until now but have been watching the post. I don't understand how you keep finding these wonderful and interesting toys. I believe the scope was "stuck" because it was closely fit up and as you indicated hadn't been removed since before Custer was on the E4 list. A little oil and removing/reinstalling it a couple times should free it up. You shouldn't need the dowel, but it's good that it is closely fit. Axel wrote a piece about adjusting these old scopes and I recommend reading it. As I recall, adjusting the elevation (if it isn't stuck) is a matter of trial and error. Adjusting the windage seems to be by drifting the front base in the dovetail, note the witness mark and stake marks on the dovetail. I suggest leaving the adjustments "as is" until handloading efforts show you have to change them. I find the original sighting to be the best indication of the load the rifle likes. Brass is going to be hard to find, it is the one caliber I don't have an acceptable donor case for. I think the best bet is to look for 6x70R cases, intended for the einstecklauf (also an interesting cartridge). This is a relatively recent cartridge and may be the best bet. The split case you showed looks like it may have been fired with a mercuric primer and handloaded. This shouldn't be a possibility with 6x70R cases. Bullets may also be a problem, the "book" indicates it needs a .260-.261" bullet like my 6.5x48R and 6.5x58R, but you should slug the barrel to be sure. You may be lucky enough that the Austrian barrel wants a .264" bullet, but if not, I am set up to resize them from .264 to .261". The original bullet was a heavy for caliber round nose bullet and modern bullets of this weight will likely be spitzer form and too long for the rifling twist. I am using 90 grain varmint and 95 grain game bullets, but am still working out the loads.
Have fun,
Mike
