If I were to build a double rifle on a shotgun action then I would use a Browning BSS 12 ga., I would have it re-hardened and be good to go with about any reasonalble double rifle load..BTW it is still going to cost you about $8000 at the least and probably more...
Based on that, you can buy a used Merkle for about the same money if you shop and argueably have a better rifle..Also the resale on shotgun actioned double rifles is zilch, and they are darn hard to move..
Personally if I couldn't afford a double rifle I would opt for a Ruger No.1 and be good to go...
I have absolutly no use for and over/under double rifle as far as a DG rifle..It's design is not such that function is reliable in that the lower barrel does not clear the action and if you are under pressure it has a tendency stop catch the ejected round on the top of the action, mostly out of human error in not forcing it open all the way, but never the less it can be an issue..That is why is has never been popular in Africa, and never will be, it just did not stand the test.
Love those browning superposed shotguns, but not the rifles.
