Birdhunter50,
That is a fine looking .405 double, thank you for posting; I located your post while doing Google searches for " simson .405 double rifles" after learning from AZDAVE that there is such a rifle.
I have been looking for a .405 double rifle and really like your work.

Can you answer a couple of questions for me?
1. You say you proofed the rifle with 300 grain bullets at 2100 fps; was this Hornady factory ammo?
2. Did you regulate it with the same ammo?
3. Is the regulation parallel and if not, at what range do the barrels cross?
4. I did not see the stock sling swivel stud on the butt stock; is it recessed into the stock?

Thank you,
CRS