Thanks Ovidio,
That explains a lot! I was aiming by lining up the front and rear sights on all three of my Carcanos, which explains the high shots. I figured it had something to do with the short length of the barrels. My Mosin M44 carbine does the same, but it's barrel is corroded near the muzzle, the others are fairly shiny and clean.
As for limbsavers, I'm tall as well (6'3") and that little piece of rubber does wonders for not just my shoulder, but the overall feel when shouldering certain rifles (Carcano M38, Mosin carbines, Jap carbines).