I really thank you people for all your intrest in my work! There are a few things I should make clear to you.
First I am not saying you can not do what I have done but keep in mind building rifles is how I make my pay check.
Second, any time you make such drastic changes as building a double rifle on a shotgun action IT HAS TO BE RE PROOFED!!!! Your life and body parts, as well as others depends on this. When re-proofing a gun it should be in a shooting fixture not your hands and you should be in a safe place. I should have gone over this earlier but I left this, probably the most important part out!!!! I do not want you people getting hurt or worse!!!!
Most guns have the proof pressures stamped on the frame it is rather easy with a good loading book and a bit of basic math to figure out if your intended cartridge falle within these pressures. If it does not the best bet is to look else where for an action. As for the proof testing load I use the German methiod which is; Max load for the cartridge and up the bullet weight 10 percent. In the case of my 450 this was an 18 grain over load of IMR 4831 which even in a case the size of the 450#2 a substancial over load.
Please do not get me wrong, I am not trying to discourage any of you but please be careful and safe and do not take chances. In my line of work I see many short cuts which can and some times do lead to disaster, I do not want any of you to be part of that. Check your pressures, Proof test and use your brain and if you need help please contact me!!!!