Carpediem,

do in deed take 500Nitro's advice, and try foremost to shoot the rifle with factory ammo over iron sights at 50 meters to check how it does this way.

As to why l/r shoots better then r/l: This is probably not a regulation issue as such, but asymmetrical tension between the barrels that plays out more pronounced when shooting r/l.

As I own a double rifle that had been regulated for iron sights only, and has a scope on it as well, I might be able to give you some insights:

From my experience, an added scope has the tendency to make the barrels cross (moving the left barrel on top and right to the right barrel in my case). Your target looks like the left barrel is already halfways on its way to move over to the right.

Depending on weight and relative position of the scope along the axis of the gun, this is more or less pronounced. Moving the scope forward, to a point where the original balance of the gun is regained, did not eliminate crossing, but brought the shots much closer together which made the scope very usable up to 60 yards. Obviously a question of eye-relief of your scope. Could only do that with a new Swaro Z6 EE, as the eye relief is huge.

Well, I had tried many loads at many different speeds but could not solve the problem until I tried this: Left barrel solid, right barrel soft. Bingo! Perfect regulation for the scoped gun.

If nothing works to your satisfaction in changing loads and bullets to attain useful regulation with a scope, I would very much recommend that you install an AIMPOINT red-dot mini-scope. They weigh almost nothing and will not alter regulation and have a practically infinite eye-relief. This will sit high enough so that you are not bothered by your Bavarian stock design and be effectively as fast in getting on target as iron sights (just easier to use). I recommend 1X magnification with a 2 MOA red dot.

http://www.aimpoint.com/o.o.i.s?id=28&prev_id=28&product_id=113